Similar to how brush assets are created and managed this
PR allows to export pose assets into a different library.
Because of this there is a limitation to this where each
asset is stored in a separate blend file.
This may be lifted in the future as there are planned changes in
the design phase: #122061
### Create Asset
Now available in the 3D viewport in the "Pose" menu: "Create Pose Asset".
The button in the Dope Sheet will now call this new operator as well.
Clicking either of those will open a popup in which you can:
* Choose the name of the asset, which library and catalog it goes into.
* Clicking "Create" will create a pose asset on disk in the given library.
It is possible to create files into an outside library or add it in the current file.
The latter option does a lot less since it basically just creates the
action and tags it as an asset.
If no Asset Shelf **AND** no Asset Browser is visible anywhere in Blender,
the Asset Shelf will be shown on the 3D viewport from which
the operator was called.
### Adjust Pose Asset
Right clicking a pose asset that has been created in the way described
before will have options to overwrite it.
Only the active object will be considered for updating a pose asset
Available Options (the latter 3 under the "Modify Pose Asset" submenu):
* Adjust Pose Asset: From the selected bones, update ONLY channels that
are also present in the asset. This is the default.
* Replace: Will completely replace the data in the Pose Asset from
the current selection
* Add: Adds the current selection to the Pose Asset. Any already existing
channels have their values updated
* Remove: Remove selected bones from the pose asset
Currently this refreshes the thumbnail. In the case of custom
thumbnails it might not be something want
### Deleting an existing Pose Asset
Right click on a Pose Asset and hit "Delete Pose Asset". Works in the shelf
and in the asset library. Doing so will pop up a confirmation dialog,
if confirming, the asset is gone forever. Deleting a local asset is basically the
same as clearing the asset. This is a bit confusing because you get
two options that basically do the same thing sometimes,
but "Delete" works in other cases as well.
I currently don't see a way around that.
Part of design #131840
Pull Request: https://projects.blender.org/blender/blender/pulls/132747