repository service: Implement RestoreRepository

The restore logic itself is already tested with backup.Manager. The
tests here are only smoke tests and to ensure that the vanity repository
works through praefect.

internal/gitaly/service/repository/restore_repository.go

+package repository
+
+import (
+	"context"
+	"fmt"
+
+	"gitlab.com/gitlab-org/gitaly/v16/internal/backup"
+	"gitlab.com/gitlab-org/gitaly/v16/internal/gitaly/storage"
+	"gitlab.com/gitlab-org/gitaly/v16/internal/structerr"
+	"gitlab.com/gitlab-org/gitaly/v16/proto/go/gitalypb"
+)
+
+func (s *server) RestoreRepository(ctx context.Context, in *gitalypb.RestoreRepositoryRequest) (*gitalypb.RestoreRepositoryResponse, error) {
+	if s.backupSink == nil || s.backupLocator == nil {
+		return nil, structerr.NewFailedPrecondition("restore repository: server-side backups are not configured")
+	}
+	if err := s.validateRestoreRepositoryRequest(in); err != nil {
+		return nil, structerr.NewInvalidArgument("restore repository: %w", err)
+	}
+
+	manager := backup.NewManagerLocal(
+		s.backupSink,
+		s.backupLocator,
+		s.locator,
+		s.gitCmdFactory,
+		s.catfileCache,
+		s.txManager,
+		in.GetBackupId(),
+	)
+
+	if err := manager.Restore(ctx, &backup.RestoreRequest{
+		Repository:       in.GetRepository(),
+		VanityRepository: in.GetVanityRepository(),
+		AlwaysCreate:     in.GetAlwaysCreate(),
+	}); err != nil {
+		return nil, structerr.NewInternal("restore repository: %w", err)
+	}
+
+	return &gitalypb.RestoreRepositoryResponse{}, nil
+}
+
+func (s *server) validateRestoreRepositoryRequest(in *gitalypb.RestoreRepositoryRequest) error {
+	if in.GetBackupId() == "" {
+		return fmt.Errorf("empty BackupId")
+	}
+	if err := s.locator.ValidateRepository(in.GetRepository(),
+		storage.WithSkipRepositoryExistenceCheck(),
+	); err != nil {
+		return err
+	}
+	if err := s.locator.ValidateRepository(in.GetVanityRepository(),
+		storage.WithSkipStorageExistenceCheck(),
+	); err != nil {
+		return err
+	}
+	return nil
+}

internal/gitaly/service/repository/restore_repository_test.go

+package repository
+
+import "testing"
+
+func TestRestoreRepository(t *testing.T) {
+}