[FIX] ScoringSheetViewer slider style and tooltip

[ZanMervic]

Issue

Fixes #6985

Description of changes

• Changes to the slider styling to suggest the slider is not interactive.
• Created a custom slider which ignores mouse events instead of disabling the default slider. By doing this, the tooltip should work on macOS.

Includes

• Code changes
• Tests
• Documentation

[codecov]

Codecov Report

Attention: Patch coverage is 30.00000% with 14 lines in your changes missing coverage. Please review.

Project coverage is 88.60%. Comparing base (7be875f) to head (2b517e7).
Report is 134 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #7024      +/-   ##
==========================================
+ Coverage   88.36%   88.60%   +0.24%     
==========================================
  Files         332      332              
  Lines       73345    73384      +39     
==========================================
+ Hits        64813    65025     +212     
+ Misses       8532     8359     -173     

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[ajdapretnar]

I like the change visually, but the tooltip doesn't work for me. Perhaps it is not necessary, since we see the exact probability below, but I kind like tooltips in general.

[janezd]

Use

painter.setBrush(QPalette().color(QPalette.WindowText))

to support dark mode.

[janezd]

This hard rectangle looks Linux-y. Perhaps change to this?

painter.drawRoundedRect(QRect(handle_rect.center().x() - 1, handle_rect.y(),
                              3, handle_rect.height()),
                        3, 3)

[janezd]

@ZanMervic, thanks for the change. Apologies that it took me so long to review this.

I made the slider a tad shorter, I think it looks nicer.

Lint failed with a complaint about accessing a private method, so I looked in. The problem is that the code didn't follow the proper Qt way for the widget to update a parent, which is by emitting a signal. I made the necessary change. Please check and -- if it's OK -- merge (or approve if you have no right to merge).