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/server/connect_middleware/activity_interceptor.go

@@ -0,0 +1,52 @@
+package connect_middleware
+
+import (
+	"context"
+	"net/http"
+	"slices"
+	"strings"
+
+	"connectrpc.com/connect"
+
+	"github.com/zitadel/zitadel/internal/activity"
+	"github.com/zitadel/zitadel/internal/api/grpc/gerrors"
+	ainfo "github.com/zitadel/zitadel/internal/api/info"
+)
+
+func ActivityInterceptor() connect.UnaryInterceptorFunc {
+	return func(handler connect.UnaryFunc) connect.UnaryFunc {
+		return func(ctx context.Context, req connect.AnyRequest) (connect.AnyResponse, error) {
+			ctx = activityInfoFromGateway(ctx, req.Header()).SetMethod(req.Spec().Procedure).IntoContext(ctx)
+			resp, err := handler(ctx, req)
+			if isResourceAPI(req.Spec().Procedure) {
+				code, _, _, _ := gerrors.ExtractZITADELError(err)
+				ctx = ainfo.ActivityInfoFromContext(ctx).SetGRPCStatus(code).IntoContext(ctx)
+				activity.TriggerGRPCWithContext(ctx, activity.ResourceAPI)
+			}
+			return resp, err
+		}
+	}
+}
+
+var resourcePrefixes = []string{
+	"/zitadel.management.v1.ManagementService/",
+	"/zitadel.admin.v1.AdminService/",
+	"/zitadel.user.v2.UserService/",
+	"/zitadel.settings.v2.SettingsService/",
+	"/zitadel.user.v2beta.UserService/",
+	"/zitadel.settings.v2beta.SettingsService/",
+	"/zitadel.auth.v1.AuthService/",
+}
+
+func isResourceAPI(method string) bool {
+	return slices.ContainsFunc(resourcePrefixes, func(prefix string) bool {
+		return strings.HasPrefix(method, prefix)
+	})
+}
+
+func activityInfoFromGateway(ctx context.Context, headers http.Header) *ainfo.ActivityInfo {
+	info := ainfo.ActivityInfoFromContext(ctx)
+	path := headers.Get(activity.PathKey)
+	requestMethod := headers.Get(activity.RequestMethodKey)
+	return info.SetPath(path).SetRequestMethod(requestMethod)
+}