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>

docs/docusaurus.config.js

@@ -337,7 +337,7 @@ module.exports = {
           },
           webkey_v2: {
             specPath:
-              ".artifacts/openapi/zitadel/webkey/v2beta/webkey_service.swagger.json",
+              ".artifacts/openapi3/zitadel/webkey/v2/webkey_service.openapi.yaml",
             outputDir: "docs/apis/resources/webkey_service_v2",
             sidebarOptions: {
               groupPathsBy: "tag",
@@ -373,7 +373,7 @@ module.exports = {
           },
           org_v2beta: {
             specPath:
-              ".artifacts/openapi/zitadel/org/v2beta/org_service.swagger.json",
+              ".artifacts/openapi3/zitadel/org/v2beta/org_service.openapi.yaml",
             outputDir: "docs/apis/resources/org_service_v2beta",
             sidebarOptions: {
               groupPathsBy: "tag",
@@ -382,16 +382,24 @@ module.exports = {
           },
           project_v2beta: {
             specPath:
-              ".artifacts/openapi/zitadel/project/v2beta/project_service.swagger.json",
+              ".artifacts/openapi3/zitadel/project/v2beta/project_service.openapi.yaml",
             outputDir: "docs/apis/resources/project_service_v2",
             sidebarOptions: {
               groupPathsBy: "tag",
               categoryLinkSource: "auto",
             },
           },
+          application_v2: {
+            specPath: ".artifacts/openapi3/zitadel/app/v2beta/app_service.openapi.yaml",
+            outputDir: "docs/apis/resources/application_service_v2",
+            sidebarOptions: {
+              groupPathsBy: "tag",
+              categoryLinkSource: "auto",
+            },
+          },
           instance_v2: {
             specPath:
-              ".artifacts/openapi/zitadel/instance/v2beta/instance_service.swagger.json",
+              ".artifacts/openapi3/zitadel/instance/v2beta/instance_service.openapi.yaml",
             outputDir: "docs/apis/resources/instance_service_v2",
             sidebarOptions: {
               groupPathsBy: "tag",