Acceptance tests for occ user:sync command

[phil-davis]

Add acceptance tests for the occ user:sync command covering:

• a full default sync -- [Tests-Only] Add user sync tests user_ldap#497
• sync a specific user -- [Tests-Only] Add user sync tests user_ldap#497
• sync a user that is a substring of some other LDAP user (e.g. sync user1 when there is also a user11 existing) - to cover code fix in PR [for 10.4] Receive multiple users from backend for user sync #36576 -- [Tests-Only] Added acceptance tests for user:sync command with super/sub-strings in user usernames user_ldap#508
• sync a user that is a substring and superstring of some local user -- [Tests-Only] Added acceptance tests for user:sync command with super/sub-strings in user usernames user_ldap#508
• sync a local user (probably should exit with success and be a NOOP) -- [Test_Only] Added acceptance test for single/multiple user:sync user_ldap#506

The tests will probably be easiest to put in the user_ldap app.

[phil-davis]

@kiranparajuli589 please also test some "error" cases, e.g. trying to sync a user that does not exist at all...

See issue owncloud/user_ldap#515

[kiranparajuli589]

@phil-davis different acceptance tests scenarios for user:sync was added..
so, closing...