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/user/v2/key_query.go

@@ -3,6 +3,7 @@ package user
 import (
 	"context"
 
+	"connectrpc.com/connect"
 	"google.golang.org/protobuf/types/known/timestamppb"
 
 	"github.com/zitadel/zitadel/internal/api/grpc/filter/v2"
@@ -12,13 +13,13 @@ import (
 	"github.com/zitadel/zitadel/pkg/grpc/user/v2"
 )
 
-func (s *Server) ListKeys(ctx context.Context, req *user.ListKeysRequest) (*user.ListKeysResponse, error) {
-	offset, limit, asc, err := filter.PaginationPbToQuery(s.systemDefaults, req.Pagination)
+func (s *Server) ListKeys(ctx context.Context, req *connect.Request[user.ListKeysRequest]) (*connect.Response[user.ListKeysResponse], error) {
+	offset, limit, asc, err := filter.PaginationPbToQuery(s.systemDefaults, req.Msg.GetPagination())
 	if err != nil {
 		return nil, err
 	}
 
-	filters, err := keyFiltersToQueries(req.Filters)
+	filters, err := keyFiltersToQueries(req.Msg.GetFilters())
 	if err != nil {
 		return nil, err
 	}
@@ -27,7 +28,7 @@ func (s *Server) ListKeys(ctx context.Context, req *user.ListKeysRequest) (*user
 			Offset:        offset,
 			Limit:         limit,
 			Asc:           asc,
-			SortingColumn: authnKeyFieldNameToSortingColumn(req.SortingColumn),
+			SortingColumn: authnKeyFieldNameToSortingColumn(req.Msg.SortingColumn),
 		},
 		Queries: filters,
 	}
@@ -49,7 +50,7 @@ func (s *Server) ListKeys(ctx context.Context, req *user.ListKeysRequest) (*user
 			ExpirationDate: timestamppb.New(key.Expiration),
 		}
 	}
-	return resp, nil
+	return connect.NewResponse(resp), nil
 }
 
 func keyFiltersToQueries(filters []*user.KeysSearchFilter) (_ []query.SearchQuery, err error) {