Removed mentions of $deriveKeyStrategy from Security phpdoc
`yii\authclient\widgets\AuthChoice` now preserves initial settings while opening popup
Fixes #4489: RBAC PhpManager wasn't saving multiple assignmentsFixes #4489: RBAC PhpManager wasn't saving multiple assignments properly
[skip ci] Fixes #4461
Fixed link
added unit test for #4489
code style + test groups
more explicit comment in phpdoc, code style
Removed unnecessary code
Fixes #4489: Fixed MySQL RBAC manager