This adds an operator `graph.select_key_handles` to the graph editor
that changes the selection of the different parts of a bezier keyframe. It
operates on all keys that are either themselves selected or have either of
their handles selected, and changes whether the key itself and/or its handles
are selected.
The operator has three options:
- `left_handle_action`
- `right_handle_action`
- `key_action`
Each of which can be set to:
- Select
- Deselect
- Keep (do nothing)
Co-authored-by: cgtinker <Denys.Hsu@gmail.com>
Pull Request: https://projects.blender.org/blender/blender/pulls/111143
be5cf8f8a1