In a Curves (not Curve) object, the MeshSequenceCache modifier is not
available from the "Add Modifier" dropdown.
However, the Alembic importer adds such a modifier onto the Curves
objects it creates. It is also possible to transfer such a modifier from
another object, regardless of its type.
Thus, this seems not to be an issue of compatibility of the modifier
with the Curves object type, but an UI/UX oversight.
`BKE_object_support_modifier_type_check` already has a correct check for
this, so just adding CURVES support to the appropriate menu.
Same is true for the POINTCLOUD type, so adding that as well.
Pull Request: https://projects.blender.org/blender/blender/pulls/128756
3b9a07d49a