This adds an operator that moves slots of slot channels selected in
the channel box to a new action.
All slots are moved together into that new action instead of
moving them into separate actions.
I think that's more reasonable because that way the "move slots into separate actions" is
still possible by selecting the slots one by one.
The "explode action" operator that does just that can be a separate operator.
The new action is named after the slot for the case when only one slot is moved.
When multiple slots are moved, the name "CombinedAction" is used.
This also adds a menu entry "Action" to the action editor.
Pull Request: https://projects.blender.org/blender/blender/pulls/128171
95b6cf0099