Expose the ID type identifier as defined by the `rna_enum_id_type_items`
enum items as `ID.id_type` in RNA.
Add some test to `id_management` ensuring that all ID types exposed in
`bpy.data` have a valid `id_type` value, i.e. that they have a matching
entry in `rna_enum_id_type_items`.
This will hopefully prevent future cases like #115151 .
9b08352b21