This is in response to feedback to the changes from #113504
While it does simplify inserting keyframes,
sometimes artists want to insert keys only to e.g. Location.
This takes longer to do now, since the option is in a menu.
This PR changes the following:
* new `K` hotkey to bring up the "Keying Set" menu.
This will always show the menu, even if a keying set is active.
* `Shift + K` will open a menu to set the active keying set
* with "Pie Menu on Drag" enabled in the user preferences,
hitting `I` and moving the mouse will bring up a pie menu
to insert only specific transform channels
Conceptually this separates the keying set behavior from the
insert keyframe behavior.
`I` will always add keyframes.
While `K` always shows keying set options.
Pull Request: https://projects.blender.org/blender/blender/pulls/115798
