Merge tag '2.1.1' into develop

Tagging version 2.1.1 2.1.1
[BUGFIX] Backend Module: Form Converter: Table 'powermail.tx_powermail_fields' doesn't exist

Database query to find old fieldsets and fields should only be executed, if there are really old tables in database

related: #61567
[BUGFIX] Powermail Plugin in QuickEdit Mode: Open a Form with the edit button

Fixed link in Backend Plugin

related: #61658
[TASK] Manual update, Version update
Merge branch 'release/2.1.2'
Merge tag '2.1.2' into develop

Tagging version 2.1.2 2.1.2