Add "Reduce Motion" option to a new `Accessibility` panel under
Preferences, User Interface.
"Reduce Motion" avoids non-essential animation effects, especially
useful for those experiencing motion sickness/vertigo.
It affects:
* Region open/close.
* Pie menus animation.
* Smooth views.
This panel in the future could host common accessibility settings such
as "Increase Contrast" or font size and weight controls that currently
are part of themes.
See PR for details and screenshots.
Co-authored-by: Harley Acheson <harley.acheson@gmail.com>
Pull Request: https://projects.blender.org/blender/blender/pulls/140873
eae4585177