AnimatableProperty trait's get_mut signature should access to resource

## What problem does this solve or what need does it fill?
to problem will be solved: can not update assets in get_mut
A description of why this particular feature should be added.
` let mesh_material_3d = entity
.get_mut::>()
.ok_or(AnimationEvaluationError::ComponentNotPresent(TypeId::of::<
MeshMaterial3d,
>(
)))?
.into_inner();`
now we have a MeshMaterial3d Component With a StandardMaterial resource, we have no way to access the referrenceof the StandardMaterial without the help of Asset,
## What solution would you like?
offer another paramerter for get_mut ,or add some method to entity ,to have ability to access resource;