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/translator.go

@@ -0,0 +1,37 @@
+package connect_middleware
+
+import (
+	"context"
+	"errors"
+
+	"github.com/zitadel/zitadel/internal/i18n"
+	"github.com/zitadel/zitadel/internal/zerrors"
+)
+
+type localizers interface {
+	Localizers() []Localizer
+}
+type Localizer interface {
+	LocalizationKey() string
+	SetLocalizedMessage(string)
+}
+
+func translateFields(ctx context.Context, object localizers, translator *i18n.Translator) {
+	if translator == nil || object == nil {
+		return
+	}
+	for _, field := range object.Localizers() {
+		field.SetLocalizedMessage(translator.LocalizeFromCtx(ctx, field.LocalizationKey(), nil))
+	}
+}
+
+func translateError(ctx context.Context, err error, translator *i18n.Translator) error {
+	if translator == nil || err == nil {
+		return err
+	}
+	caosErr := new(zerrors.ZitadelError)
+	if errors.As(err, &caosErr) {
+		caosErr.SetMessage(translator.LocalizeFromCtx(ctx, caosErr.GetMessage(), nil))
+	}
+	return err
+}