Blender Git Loki

Asset: Merge asset library/list refresh operators

In rBdcdbaf89bd11, I introduced a new operator
(`file.asset_library_refresh()`) to handle Asset Browser refreshing more
separate from File Browser refreshing. However, there already was
`asset.asset_list_refresh()`, which at this point only works for asset
view templates, but was intended to cover the Asset Browser case in
future too. This would happen once the Asset Browser uses the asset list
design of the asset view template.

So rather than having two operators for refreshing asset library data,
have one that just handles both cases, until they converge into one.
This avoids changes to the Python API in future (deprecating/changing
operators).

Differential Revision: https://developer.blender.org/D13239