Fix new created dock under current selected

Description

Currently a new dock is created below other docks, this is because if there are already multiple docks, the last dockArea must be passed as argument.

Introduced with !549 (merged)

Conformity

• Changelog entry
• Unit tests
• Update INSTALL
• Downport: To 2.11: 07db527b
• Fixes:

When external dependencies are removed

• Reporting to ...