Move some asymkey functions to service layer (#28894)

After the moving, all models will not depend on `util.Rename` so that I
can do next step refactoring.

services/asymkey/ssh_key_principals.go

@@ -0,0 +1,54 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package asymkey
+
+import (
+	"context"
+	"fmt"
+
+	asymkey_model "code.gitea.io/gitea/models/asymkey"
+	"code.gitea.io/gitea/models/db"
+	"code.gitea.io/gitea/models/perm"
+)
+
+// AddPrincipalKey adds new principal to database and authorized_principals file.
+func AddPrincipalKey(ctx context.Context, ownerID int64, content string, authSourceID int64) (*asymkey_model.PublicKey, error) {
+	dbCtx, committer, err := db.TxContext(ctx)
+	if err != nil {
+		return nil, err
+	}
+	defer committer.Close()
+
+	// Principals cannot be duplicated.
+	has, err := db.GetEngine(dbCtx).
+		Where("content = ? AND type = ?", content, asymkey_model.KeyTypePrincipal).
+		Get(new(asymkey_model.PublicKey))
+	if err != nil {
+		return nil, err
+	} else if has {
+		return nil, asymkey_model.ErrKeyAlreadyExist{
+			Content: content,
+		}
+	}
+
+	key := &asymkey_model.PublicKey{
+		OwnerID:       ownerID,
+		Name:          content,
+		Content:       content,
+		Mode:          perm.AccessModeWrite,
+		Type:          asymkey_model.KeyTypePrincipal,
+		LoginSourceID: authSourceID,
+	}
+	if err = db.Insert(dbCtx, key); err != nil {
+		return nil, fmt.Errorf("addKey: %w", err)
+	}
+
+	if err = committer.Commit(); err != nil {
+		return nil, err
+	}
+
+	committer.Close()
+
+	return key, RewriteAllPrincipalKeys(ctx)
+}