feat: add new api services (#5619)

* feat: add new services

* improve demos and comments

* remove unused field

* add comment to demo proto calls

* Apply suggestions from code review

Co-authored-by: Silvan <silvan.reusser@gmail.com>

---------

Co-authored-by: Silvan <silvan.reusser@gmail.com>

internal/api/grpc/session/v2/session.go

@@ -0,0 +1,18 @@
+package session
+
+import (
+	"context"
+
+	"github.com/zitadel/zitadel/internal/api/authz"
+	"github.com/zitadel/zitadel/pkg/grpc/session/v2alpha"
+	"github.com/zitadel/zitadel/pkg/grpc/user/v2alpha"
+)
+
+func (s *Server) GetSession(ctx context.Context, req *session.GetSessionRequest) (*session.GetSessionResponse, error) {
+	return &session.GetSessionResponse{
+		Session: &session.Session{
+			Id:   req.Id,
+			User: &user.User{Id: authz.GetCtxData(ctx).UserID},
+		},
+	}, nil
+}