Workspaces [FILTER_ID_WS] were in the `Environment` category
IDFilterBoolean, whereas they are in the `Miscellaneous` category in
`rna_def_fileselect_asset_params`.
Make this consistent ['Miscellaneous'] in both cases.
(note this was already done in rB2c317457cbf2 for the file browser case)
Spotted while looking into T83983.
Maniphest Tasks: T83983
Differential Revision: https://developer.blender.org/D9911
fab772860d