Away: Allow editing of own entries

[blackcoder87]

Description

• Allow editing of own entries.
• Code improvements.
• Fix issue with a previous change (invalid class name).

Fixes #781

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)

This PR has been tested in the following browsers:

• Chrome
• Firefox
• Opera
• Edge

[hhunderter]

https://github.com/IlchCMS/Ilch-2.0/pull/1138/files#diff-682c474ace0388d75abaaea883e5eb0a5c9e25cab39f97231155ffdcc71d0038R94

$userGroups = $awayGroupMapper->getGroups();
$users = $userMapper->getUserListByGroupId($userGroups, 1);

Expected parameter of type 'int', 'array|null' provided

hab zwar keinen Fehler bekommen aber sollten wir aufn Schirm behalten?

[blackcoder87]

#1145