Add MTIA DeviceType for Meta training and inference devices (#92232)
Summary: This adds a new MTIA DeviceType which is associated with the MTIA DispatchKey and will be used for the Meta in-house training and inference accelerators.
Test Plan: All CI should pass.
Differential Revision: D42526044
Pull Request resolved: https://github.com/pytorch/pytorch/pull/92232
Approved by: https://github.com/ezyang
