feat(api): enhance Actions Secrets Management API for repository (#30656)

- Add endpoint to list repository action secrets in API routes
- Implement `ListActionsSecrets` function to retrieve action secrets
from the database
- Update Swagger documentation to include the new
`/repos/{owner}/{repo}/actions/secrets` endpoint
- Add `actions` package import and define new routes for actions,
secrets, variables, and runners in `api.go`.
- Refactor action-related API functions into `Action` struct methods in
`org/action.go` and `repo/action.go`.
- Remove `actionAPI` struct and related functions, replacing them with
`NewAction()` calls.
- Rename `variables.go` to `action.go` in `org` directory.
- Delete `runners.go` and `secrets.go` in both `org` and `repo`
directories, consolidating their content into `action.go`.
- Update copyright year and add new imports in `org/action.go`.
- Implement `API` interface in `services/actions/interface.go` for
action-related methods.
- Remove individual action-related functions and replace them with
methods on the `Action` struct in `repo/action.go`.

---------

Signed-off-by: Bo-Yi Wu <appleboy.tw@gmail.com>
Signed-off-by: appleboy <appleboy.tw@gmail.com>

services/actions/interface.go

@@ -0,0 +1,28 @@
+// Copyright 2024 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+package actions
+
+import "code.gitea.io/gitea/services/context"
+
+// API for actions of a repository or organization
+type API interface {
+	// ListActionsSecrets list secrets
+	ListActionsSecrets(*context.APIContext)
+	// CreateOrUpdateSecret create or update a secret
+	CreateOrUpdateSecret(*context.APIContext)
+	// DeleteSecret delete a secret
+	DeleteSecret(*context.APIContext)
+	// ListVariables list variables
+	ListVariables(*context.APIContext)
+	// GetVariable get a variable
+	GetVariable(*context.APIContext)
+	// DeleteVariable delete a variable
+	DeleteVariable(*context.APIContext)
+	// CreateVariable create a variable
+	CreateVariable(*context.APIContext)
+	// UpdateVariable update a variable
+	UpdateVariable(*context.APIContext)
+	// GetRegistrationToken get registration token
+	GetRegistrationToken(*context.APIContext)
+}