Forward all scroll events in text area widgets to parent

[vkbo]

Summary:

This PR adds an event filter that will capture any mouse wheel scroll event on a widget and forward the event to the wheelEvent handler of the root widget. This solves the issue that scroll events in widget margins are ignored.

Related Issue(s):

Closes #1425
Duplicate #1474

Reviewer's Checklist:

• The header of all files contain a reference to the repository license
• The overall test coverage is increased or remains the same as before
• All tests are passing
• All flake8 checks are passing and the style guide is followed
• Documentation (as docstrings) is complete and understandable
• Only files that have been actively changed are committed