Add F-Curve management functions on ChannelBags
(`channelbag.fcurves.xxx`) that are very similar to the legacy Action
functions `Action.fcurves.xxx`.
```python
channelbag = strip.channelbags.new(slot)
fcurve = channelbag.fcurves.new("rotation_quaternion", index=1)
assert channelbag.fcurves[0] == fcurve
channelbag.fcurves.remove(fcurve)
channelbag.fcurves.clear()
```
Pull Request: https://projects.blender.org/blender/blender/pulls/124987
RNA API for creating & removing channelbags, as well as a path function
to construct RNA paths for channelbags.
```python
action = bpy.data.actions.new('TestAction')
slot = action.slots.new()
slot.name = 'OBTest'
layer = action.layers.new(name="Layer")
strip = layer.strips.new(type='KEYFRAME')
# New in this commit:
channelbag = strip.channelbags.new(slot)
strip.channelbags.remove(channelbag)
```
Pull Request: https://projects.blender.org/blender/blender/pulls/124793
Rename "Animation data-block" to "Action" or "Layered Action", where
appropriate. Some uses of the term actually refer to the `AnimData`
struct, in which case they were left as-is.
No real functional changes, just changing some messages & descriptions.
Pull Request: https://projects.blender.org/blender/blender/pulls/124170
Rename 'Binding' to 'Slot'. The old term was causing all kind of
confusion, and 'slot' was considered to be a better term for the
intended functionality.
This commit breaks existing blend files that were using the new layered
Action for their animation. The animation data will be lost due to the
rename, as there is no versioning code or DNA renaming logic. At this
time the new system is still marked as experimental, so shouldn't be
used for anything serious anyway.
Pull Request: https://projects.blender.org/blender/blender/pulls/124170
Add guards to the RNA code to prevent the creation of legacy data on a
layered Action, and vice versa.
On a legacy Action, it is now impossible to create new layers or bindings.
On a layered Action, it's now impossible to create legacy F-Curves or
groups.
Refactor: Anim: rename bl_animation_id.py to bl_animation_action.py
The `Animation` datablock is no more, and this file tests `Action`.
No functional changes.
Pull Request: https://projects.blender.org/blender/blender/pulls/122483
