Move user creation logic to a separate service in core

[sharidas]

Move user creation logic to a separate service in
core.

Signed-off-by: Sujith H sharidasan@owncloud.com

[sharidas]

• Requires Move user creation to a separate service owncloud/core#35972

[jvillafanez]

Update the link in the previous post because I clicked on a closed unmerged ticket

[jvillafanez]

Code looks good, waiting for the test results

[sharidas]

This PR is dependant on owncloud/core#35972. There is a class from the core pr being used in this change set.

[sharidas]

Looking at the failure in the unit tests

• Which are not part of this PR : ChangePasswordControllerTest, PageControllerTest, SubadminMiddlewareTest, SubadminMiddlewareTest
  Are having problems because the fact, that https://github.com/owncloud/core/blob/master/lib/public/IGroupManager.php does not have:
  public function getSubAdmin(); and public function inGroup($uid, $gid);
  Looking further I have also noticed that we have a missing phpdoc in https://github.com/owncloud/core/blob/master/lib/private/Group/Manager.php#L489.

@DeepDiver1975 It would be nice if you could share your opinion or suggestion on how to move ahead with this PR, as its user_management app.