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/org/v2beta/helper.go

@@ -3,6 +3,7 @@ package org
 import (
 	"context"
 
+	"connectrpc.com/connect"
 	"google.golang.org/protobuf/types/known/timestamppb"
 
 	// TODO fix below
@@ -71,7 +72,7 @@ func OrgStateToPb(state domain.OrgState) v2beta_org.OrgState {
 	}
 }
 
-func createdOrganizationToPb(createdOrg *command.CreatedOrg) (_ *org.CreateOrganizationResponse, err error) {
+func createdOrganizationToPb(createdOrg *command.CreatedOrg) (_ *connect.Response[org.CreateOrganizationResponse], err error) {
 	admins := make([]*org.OrganizationAdmin, len(createdOrg.OrgAdmins))
 	for i, admin := range createdOrg.OrgAdmins {
 		switch admin := admin.(type) {
@@ -95,11 +96,11 @@ func createdOrganizationToPb(createdOrg *command.CreatedOrg) (_ *org.CreateOrgan
 			}
 		}
 	}
-	return &org.CreateOrganizationResponse{
+	return connect.NewResponse(&org.CreateOrganizationResponse{
 		CreationDate:       timestamppb.New(createdOrg.ObjectDetails.EventDate),
 		Id:                 createdOrg.ObjectDetails.ResourceOwner,
 		OrganizationAdmins: admins,
-	}, nil
+	}), nil
 }
 
 func OrgViewsToPb(orgs []*query.Org) []*v2beta_org.Organization {