feat: exchange gRPC server implementation to connectRPC (#10145)

# Which Problems Are Solved

The current maintained gRPC server in combination with a REST (grpc)
gateway is getting harder and harder to maintain. Additionally, there
have been and still are issues with supporting / displaying `oneOf`s
correctly.
We therefore decided to exchange the server implementation to
connectRPC, which apart from supporting connect as protocol, also also
"standard" gRCP clients as well as HTTP/1.1 / rest like clients, e.g.
curl directly call the server without any additional gateway.

# How the Problems Are Solved

- All v2 services are moved to connectRPC implementation. (v1 services
are still served as pure grpc servers)
- All gRPC server interceptors were migrated / copied to a corresponding
connectRPC interceptor.
- API.ListGrpcServices and API. ListGrpcMethods were changed to include
the connect services and endpoints.
- gRPC server reflection was changed to a `StaticReflector` using the
`ListGrpcServices` list.
- The `grpc.Server` interfaces was split into different combinations to
be able to handle the different cases (grpc server and prefixed gateway,
connect server with grpc gateway, connect server only, ...)
- Docs of services serving connectRPC only with no additional gateway
(instance, webkey, project, app, org v2 beta) are changed to expose that
- since the plugin is not yet available on buf, we download it using
`postinstall` hook of the docs

# Additional Changes

- WebKey service is added as v2 service (in addition to the current
v2beta)

# Additional Context

closes #9483

---------

Co-authored-by: Elio Bischof <elio@zitadel.com>

internal/api/grpc/session/v2beta/session.go

@@ -6,6 +6,7 @@ import (
 	"net/http"
 	"time"
 
+	"connectrpc.com/connect"
 	"github.com/muhlemmer/gu"
 	"golang.org/x/text/language"
 	"google.golang.org/protobuf/types/known/structpb"
@@ -31,18 +32,18 @@ var (
 	}
 )
 
-func (s *Server) GetSession(ctx context.Context, req *session.GetSessionRequest) (*session.GetSessionResponse, error) {
-	res, err := s.query.SessionByID(ctx, true, req.GetSessionId(), req.GetSessionToken(), s.checkPermission)
+func (s *Server) GetSession(ctx context.Context, req *connect.Request[session.GetSessionRequest]) (*connect.Response[session.GetSessionResponse], error) {
+	res, err := s.query.SessionByID(ctx, true, req.Msg.GetSessionId(), req.Msg.GetSessionToken(), s.checkPermission)
 	if err != nil {
 		return nil, err
 	}
-	return &session.GetSessionResponse{
+	return connect.NewResponse(&session.GetSessionResponse{
 		Session: sessionToPb(res),
-	}, nil
+	}), nil
 }
 
-func (s *Server) ListSessions(ctx context.Context, req *session.ListSessionsRequest) (*session.ListSessionsResponse, error) {
-	queries, err := listSessionsRequestToQuery(ctx, req)
+func (s *Server) ListSessions(ctx context.Context, req *connect.Request[session.ListSessionsRequest]) (*connect.Response[session.ListSessionsResponse], error) {
+	queries, err := listSessionsRequestToQuery(ctx, req.Msg)
 	if err != nil {
 		return nil, err
 	}
@@ -50,18 +51,18 @@ func (s *Server) ListSessions(ctx context.Context, req *session.ListSessionsRequ
 	if err != nil {
 		return nil, err
 	}
-	return &session.ListSessionsResponse{
+	return connect.NewResponse(&session.ListSessionsResponse{
 		Details:  object.ToListDetails(sessions.SearchResponse),
 		Sessions: sessionsToPb(sessions.Sessions),
-	}, nil
+	}), nil
 }
 
-func (s *Server) CreateSession(ctx context.Context, req *session.CreateSessionRequest) (*session.CreateSessionResponse, error) {
-	checks, metadata, userAgent, lifetime, err := s.createSessionRequestToCommand(ctx, req)
+func (s *Server) CreateSession(ctx context.Context, req *connect.Request[session.CreateSessionRequest]) (*connect.Response[session.CreateSessionResponse], error) {
+	checks, metadata, userAgent, lifetime, err := s.createSessionRequestToCommand(ctx, req.Msg)
 	if err != nil {
 		return nil, err
 	}
-	challengeResponse, cmds, err := s.challengesToCommand(req.GetChallenges(), checks)
+	challengeResponse, cmds, err := s.challengesToCommand(req.Msg.GetChallenges(), checks)
 	if err != nil {
 		return nil, err
 	}
@@ -71,43 +72,43 @@ func (s *Server) CreateSession(ctx context.Context, req *session.CreateSessionRe
 		return nil, err
 	}
 
-	return &session.CreateSessionResponse{
+	return connect.NewResponse(&session.CreateSessionResponse{
 		Details:      object.DomainToDetailsPb(set.ObjectDetails),
 		SessionId:    set.ID,
 		SessionToken: set.NewToken,
 		Challenges:   challengeResponse,
-	}, nil
+	}), nil
 }
 
-func (s *Server) SetSession(ctx context.Context, req *session.SetSessionRequest) (*session.SetSessionResponse, error) {
-	checks, err := s.setSessionRequestToCommand(ctx, req)
+func (s *Server) SetSession(ctx context.Context, req *connect.Request[session.SetSessionRequest]) (*connect.Response[session.SetSessionResponse], error) {
+	checks, err := s.setSessionRequestToCommand(ctx, req.Msg)
 	if err != nil {
 		return nil, err
 	}
-	challengeResponse, cmds, err := s.challengesToCommand(req.GetChallenges(), checks)
+	challengeResponse, cmds, err := s.challengesToCommand(req.Msg.GetChallenges(), checks)
 	if err != nil {
 		return nil, err
 	}
 
-	set, err := s.command.UpdateSession(ctx, req.GetSessionId(), cmds, req.GetMetadata(), req.GetLifetime().AsDuration())
+	set, err := s.command.UpdateSession(ctx, req.Msg.GetSessionId(), cmds, req.Msg.GetMetadata(), req.Msg.GetLifetime().AsDuration())
 	if err != nil {
 		return nil, err
 	}
-	return &session.SetSessionResponse{
+	return connect.NewResponse(&session.SetSessionResponse{
 		Details:      object.DomainToDetailsPb(set.ObjectDetails),
 		SessionToken: set.NewToken,
 		Challenges:   challengeResponse,
-	}, nil
+	}), nil
 }
 
-func (s *Server) DeleteSession(ctx context.Context, req *session.DeleteSessionRequest) (*session.DeleteSessionResponse, error) {
-	details, err := s.command.TerminateSession(ctx, req.GetSessionId(), req.GetSessionToken())
+func (s *Server) DeleteSession(ctx context.Context, req *connect.Request[session.DeleteSessionRequest]) (*connect.Response[session.DeleteSessionResponse], error) {
+	details, err := s.command.TerminateSession(ctx, req.Msg.GetSessionId(), req.Msg.GetSessionToken())
 	if err != nil {
 		return nil, err
 	}
-	return &session.DeleteSessionResponse{
+	return connect.NewResponse(&session.DeleteSessionResponse{
 		Details: object.DomainToDetailsPb(details),
-	}, nil
+	}), nil
 }
 
 func sessionsToPb(sessions []*query.Session) []*session.Session {