feat: user v3 contact email and phone (#8644)

# Which Problems Are Solved

Endpoints to maintain email and phone contact on user v3 are not
implemented.

# How the Problems Are Solved

Add 3 endpoints with SetContactEmail, VerifyContactEmail and
ResendContactEmailCode.
Add 3 endpoints with SetContactPhone, VerifyContactPhone and
ResendContactPhoneCode.
Refactor the logic how contact is managed in the user creation and
update.

# Additional Changes

None

# Additional Context

- part of https://github.com/zitadel/zitadel/issues/6433

---------

Co-authored-by: Livio Spring <livio.a@gmail.com>

internal/api/grpc/resources/user/v3alpha/query.go

@@ -0,0 +1,14 @@
+package user
+
+import (
+	"context"
+
+	user "github.com/zitadel/zitadel/pkg/grpc/resources/user/v3alpha"
+)
+
+func (s *Server) SearchUsers(ctx context.Context, _ *user.SearchUsersRequest) (_ *user.SearchUsersResponse, err error) {
+	if err := checkUserSchemaEnabled(ctx); err != nil {
+		return nil, err
+	}
+	return &user.SearchUsersResponse{}, nil
+}