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

models/fixtures/user.yml

@@ -47,7 +47,7 @@
   avatar_email: user3@example.com
   num_repos: 3
   num_members: 2
-  num_teams: 2
+  num_teams: 3
 
 -
   id: 4
@@ -266,7 +266,7 @@
   num_repos: 2
   is_active: true
   num_members: 2
-  num_teams: 1
+  num_teams: 3
 
 -
   id: 18