Add Action + Action Slot selectors to various Property Editor tabs.
This follows the pattern established in
f917b60036.
Support for `CacheFile` data-blocks is not included here. That needs
some discussion, as currently its interface is part of the Modifier
stack (and thus implemented in C++ and not Python, and using a
different layout).
Since this PR is about adding to the Property Editor, some data-blocks
that have no representation there are thus excluded (like `Mask`).
Even when they could actually use an Action+Slot selector somewhere.
Pull Request: https://projects.blender.org/blender/blender/pulls/127074
383c3c8253