Move the following BKE functions to the `animrig::Action` class. Some of
those will be extended to support slots in a future commit; for now they
still operate on all F-Curves in the Action.
| Old | New |
|---------------------------------|-------------------------------------|
| `BKE_action_frame_range_calc()` | `Action::get_frame_range_of_keys()` |
| `BKE_action_frame_range_get()` | `Action::get_frame_range()` |
| `BKE_action_has_motion()` | `Action::has_keyframes()` |
| `BKE_action_has_single_frame()` | `Action::has_single_frame()` |
| `BKE_action_is_cyclic()` | `Action::is_cyclic()` |
Implementations have been copied from the BKE functions. The frame range
functions now return `float2` instead of requiring two `float *r_…`
return parameters.
The `has_motion` function is now renamed to `has_keyframes`, as that is
what the implementation was actually testing for.
The functions now no longer are null-safe. The BKE functions handled a
null action pointer, but IMO that doesn't make sense, and in none of the
call sites I could find where this would actually be valid.
No functional changes.
Ref: #127489
Pull Request: https://projects.blender.org/blender/blender/pulls/127512
b952782a44