Integrate memory planning into Vulkan delegate (#1898)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/1898

## Context

Final changeset to integrate memory planning into the Vulkan delegate. Previously [PR #1868](https://github.com/pytorch/executorch/pull/1868 ) allowed the `greedy` memory algorithm to record the shared object index as `mem_obj_id` which can be used to construct `SharedObject` instances in the Vulkan `ComputeGraph`, which was added in [PR #118756](https://github.com/pytorch/pytorch/pull/118756).

Reviewed By: jorgep31415

Differential Revision: D53592204

fbshipit-source-id: 6d9dcaf4c7dc00f6734d842c7b03d7b925c76569