Add tag protection (#15629)

* Added tag protection in hook.

* Prevent UI tag creation if protected.

* Added settings page.

* Added tests.

* Added suggestions.

* Moved tests.

* Use individual errors.

* Removed unneeded methods.

* Switched delete selector.

* Changed method names.

* No reason to be unique.

* Allow editing of protected tags.

* Removed unique key from migration.

* Added docs page.

* Changed date.

* Respond with 404 to not found tags.

* Replaced glob with regex pattern.

* Added support for glob and regex pattern.

* Updated documentation.

* Changed white* to allow*.

* Fixed edit button link.

* Added cancel button.

Co-authored-by: zeripath <art27@cantab.net>
Co-authored-by: Lunny Xiao <xiaolunwen@gmail.com>

services/forms/repo_tag_form.go

@@ -0,0 +1,27 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package forms
+
+import (
+	"net/http"
+
+	"code.gitea.io/gitea/modules/context"
+	"code.gitea.io/gitea/modules/web/middleware"
+
+	"gitea.com/go-chi/binding"
+)
+
+// ProtectTagForm form for changing protected tag settings
+type ProtectTagForm struct {
+	NamePattern    string `binding:"Required;GlobOrRegexPattern"`
+	AllowlistUsers string
+	AllowlistTeams string
+}
+
+// Validate validates the fields
+func (f *ProtectTagForm) Validate(req *http.Request, errs binding.Errors) binding.Errors {
+	ctx := context.GetContext(req)
+	return middleware.Validate(errs, ctx.Data, f, ctx.Locale)
+}