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/action/v2beta/target.go

@@ -3,6 +3,7 @@ package action
 import (
 	"context"
 
+	"connectrpc.com/connect"
 	"github.com/muhlemmer/gu"
 	"google.golang.org/protobuf/types/known/timestamppb"
 
@@ -13,8 +14,8 @@ import (
 	action "github.com/zitadel/zitadel/pkg/grpc/action/v2beta"
 )
 
-func (s *Server) CreateTarget(ctx context.Context, req *action.CreateTargetRequest) (*action.CreateTargetResponse, error) {
-	add := createTargetToCommand(req)
+func (s *Server) CreateTarget(ctx context.Context, req *connect.Request[action.CreateTargetRequest]) (*connect.Response[action.CreateTargetResponse], error) {
+	add := createTargetToCommand(req.Msg)
 	instanceID := authz.GetInstance(ctx).InstanceID()
 	createdAt, err := s.command.AddTarget(ctx, add, instanceID)
 	if err != nil {
@@ -24,16 +25,16 @@ func (s *Server) CreateTarget(ctx context.Context, req *action.CreateTargetReque
 	if !createdAt.IsZero() {
 		creationDate = timestamppb.New(createdAt)
 	}
-	return &action.CreateTargetResponse{
+	return connect.NewResponse(&action.CreateTargetResponse{
 		Id:           add.AggregateID,
 		CreationDate: creationDate,
 		SigningKey:   add.SigningKey,
-	}, nil
+	}), nil
 }
 
-func (s *Server) UpdateTarget(ctx context.Context, req *action.UpdateTargetRequest) (*action.UpdateTargetResponse, error) {
+func (s *Server) UpdateTarget(ctx context.Context, req *connect.Request[action.UpdateTargetRequest]) (*connect.Response[action.UpdateTargetResponse], error) {
 	instanceID := authz.GetInstance(ctx).InstanceID()
-	update := updateTargetToCommand(req)
+	update := updateTargetToCommand(req.Msg)
 	changedAt, err := s.command.ChangeTarget(ctx, update, instanceID)
 	if err != nil {
 		return nil, err
@@ -42,15 +43,15 @@ func (s *Server) UpdateTarget(ctx context.Context, req *action.UpdateTargetReque
 	if !changedAt.IsZero() {
 		changeDate = timestamppb.New(changedAt)
 	}
-	return &action.UpdateTargetResponse{
+	return connect.NewResponse(&action.UpdateTargetResponse{
 		ChangeDate: changeDate,
 		SigningKey: update.SigningKey,
-	}, nil
+	}), nil
 }
 
-func (s *Server) DeleteTarget(ctx context.Context, req *action.DeleteTargetRequest) (*action.DeleteTargetResponse, error) {
+func (s *Server) DeleteTarget(ctx context.Context, req *connect.Request[action.DeleteTargetRequest]) (*connect.Response[action.DeleteTargetResponse], error) {
 	instanceID := authz.GetInstance(ctx).InstanceID()
-	deletedAt, err := s.command.DeleteTarget(ctx, req.GetId(), instanceID)
+	deletedAt, err := s.command.DeleteTarget(ctx, req.Msg.GetId(), instanceID)
 	if err != nil {
 		return nil, err
 	}
@@ -58,9 +59,9 @@ func (s *Server) DeleteTarget(ctx context.Context, req *action.DeleteTargetReque
 	if !deletedAt.IsZero() {
 		deletionDate = timestamppb.New(deletedAt)
 	}
-	return &action.DeleteTargetResponse{
+	return connect.NewResponse(&action.DeleteTargetResponse{
 		DeletionDate: deletionDate,
-	}, nil
+	}), nil
 }
 
 func createTargetToCommand(req *action.CreateTargetRequest) *command.AddTarget {