Update on "[ET Device Support] Schema changes: device info on Tensor and buffer-level device array"

This diff adds device placement information to the ExecuTorch schema to support representing tensor-level device type information, which will be the basic requirement for the following tensor_parser updates.

This is part of the Phase 1 implementation to make ET device type work E2E without user-specified device placement.

Design doc: https://docs.google.com/document/d/1lwd9BlohmwkN5EEvRulO_b-XnZBwv1nMb5l2K3jfuwA/edit?tab=t.0#heading=h.o6anuvkix4bu

Differential Revision: [D93635657](https://our.internmc.facebook.com/intern/diff/D93635657/)

[ghstack-poisoned]

Author: Gasoonjia

schema/program.fbs

@@ -63,6 +63,7 @@ enum TensorDataLocation : byte {
 }
 
 // Device type enum indicating where a tensor resides or should be allocated.
+// Please keep this in sync with executorch/runtime/core/portable_type/device.h
 enum DeviceType : byte {
   CPU = 0,
   CUDA = 1,