T30272 Fix group index inconsistenties
Summary:
Added methods for getting and setting group names
Corrected default name for unnamed groups (numbering starts now with 1)
+ added support of group names
Test Plan: code review, UI test (check if default group names now start with 1)
Reviewers: O1 MITK Reviewer Group I, s434n, kislinsk
Reviewed By: O1 MITK Reviewer Group I, s434n, kislinsk
Subscribers: s434n
Maniphest Tasks: T30272
Differential Revision: https://phabricator.mitk.org/D930