[Feature Request] Validate resource lifetimes in Mesh Draw Commands to help debug dangling pointers.

Mesh draw commands don't hold strong references to resources. When caching mesh draw commands, their lifetimes can match the parent scene proxy, which can be very long. This increases the chance that resources being added to mesh draw commands have a smaller lifetime and it can be difficult to track when those resources cause crashes.

It would be helpful to have a validation layer that tracks the lifetime of these resources and warns the user when they delete a resource but don't delete the respective mesh draw command.