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/gerrors/zitadel_errors.go

@@ -3,10 +3,12 @@ package gerrors
 import (
 	"errors"
 
+	"connectrpc.com/connect"
 	"github.com/jackc/pgx/v5/pgconn"
 	"github.com/zitadel/logging"
 	"google.golang.org/grpc/codes"
 	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/proto"
 	"google.golang.org/protobuf/protoadapt"
 
 	commandErrors "github.com/zitadel/zitadel/internal/command/errors"
@@ -36,6 +38,30 @@ func ZITADELToGRPCError(err error) error {
 	return s.Err()
 }
 
+func ZITADELToConnectError(err error) error {
+	if err == nil {
+		return nil
+	}
+	connectError := new(connect.Error)
+	if errors.As(err, &connectError) {
+		return err
+	}
+	code, key, id, ok := ExtractZITADELError(err)
+	if !ok {
+		return status.Convert(err).Err()
+	}
+	msg := key
+	msg += " (" + id + ")"
+
+	errorInfo := getErrorInfo(id, key, err)
+
+	cErr := connect.NewError(connect.Code(code), errors.New(msg))
+	if detail, detailErr := connect.NewErrorDetail(errorInfo.(proto.Message)); detailErr == nil {
+		cErr.AddDetail(detail)
+	}
+	return cErr
+}
+
 func ExtractZITADELError(err error) (c codes.Code, msg, id string, ok bool) {
 	if err == nil {
 		return codes.OK, "", "", false