Restrict permission check on repositories and fix some problems (#5314)

* fix units permission problems

* fix some bugs and merge LoadUnits to repoAssignment

* refactor permission struct and add some copyright heads

* remove unused codes

* fix routes units check

* improve permission check

* add unit tests for permission

* fix typo

* fix tests

* fix some routes

* fix api permission check

* improve permission check

* fix some permission check

* fix tests

* fix tests

* improve some permission check

* fix some permission check

* refactor AccessLevel

* fix bug

* fix tests

* fix tests

* fix tests

* fix AccessLevel

* rename CanAccess

* fix tests

* fix comment

* fix bug

* add missing unit for test repos

* fix bug

* rename some functions

* fix routes check

templates/repo/diff/comments.tmpl

@@ -21,7 +21,7 @@
 				{{end}}
 			{{end}}
 			{{template "repo/issue/view_content/add_reaction" Dict "ctx" $ "ActionURL" (Printf "%s/comments/%d/reactions" $.root.RepoLink .ID) }}
-			{{if or $.root.IsRepositoryAdmin (eq .Poster.ID $.root.SignedUserID)}}
+			{{if or $.root.Permission.IsAdmin (eq .Poster.ID $.root.SignedUserID)}}
 				<div class="item action">
 					<a class="edit-content" href="#"><i class="octicon octicon-pencil"></i></a>
 					<a class="delete-comment" href="#" data-comment-id={{.HashTag}} data-url="{{$.root.RepoLink}}/comments/{{.ID}}/delete" data-locale="{{$.root.i18n.Tr "repo.issues.delete_comment_confirm"}}"><i class="octicon octicon-x"></i></a>