Move package settings to package instead of being tied to version (#37026)

Unties settings page from package version and adds button to delete the
package version
Settings page now allows for deletion of entire package and it's
versions as opposed to a single version

Adds an API endpoint to delete the entire package with all versions from
registry

fixes: https://github.com/go-gitea/gitea/issues/36904

Co-Authored-By: gemini-3-flash

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Giteabot <teabot@gitea.io>

templates/admin/packages/list.tmpl

@@ -89,7 +89,7 @@
 	</div>
 
 <form class="ui small modal form-fetch-action" method="post" id="admin-package-delete-modal">
-	<div class="header">{{svg "octicon-trash"}} {{ctx.Locale.Tr "packages.settings.delete"}}</div>
+	<div class="header">{{svg "octicon-trash"}} {{ctx.Locale.Tr "packages.settings.delete.version"}}</div>
 	<div class="content">
 		{{ctx.Locale.Tr "packages.settings.delete.notice" (HTMLFormat `<span class="%s"></span>` "package-name") (HTMLFormat `<span class="%s"></span>` "package-version")}}
 	</div>