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
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