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/passkey_test.go

@@ -123,11 +123,11 @@ func Test_passkeyRegistrationDetailsToPb(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			got, err := passkeyRegistrationDetailsToPb(tt.args.details, tt.args.err)
 			require.ErrorIs(t, err, tt.wantErr)
-			if !proto.Equal(tt.want, got) {
+			if tt.want != nil && !proto.Equal(tt.want, got.Msg) {
 				t.Errorf("Not equal:\nExpected\n%s\nActual:%s", tt.want, got)
 			}
 			if tt.want != nil {
-				grpc.AllFieldsSet(t, got.ProtoReflect())
+				grpc.AllFieldsSet(t, got.Msg.ProtoReflect())
 			}
 		})
 	}
@@ -181,7 +181,9 @@ func Test_passkeyDetailsToPb(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			got, err := passkeyDetailsToPb(tt.args.details, tt.args.err)
 			require.ErrorIs(t, err, tt.args.err)
-			assert.Equal(t, tt.want, got)
+			if tt.want != nil {
+				assert.Equal(t, tt.want, got.Msg)
+			}
 		})
 	}
 }
@@ -242,9 +244,9 @@ func Test_passkeyCodeDetailsToPb(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			got, err := passkeyCodeDetailsToPb(tt.args.details, tt.args.err)
 			require.ErrorIs(t, err, tt.args.err)
-			assert.Equal(t, tt.want, got)
 			if tt.want != nil {
-				grpc.AllFieldsSet(t, got.ProtoReflect())
+				assert.Equal(t, tt.want, got.Msg)
+				grpc.AllFieldsSet(t, got.Msg.ProtoReflect())
 			}
 		})
 	}