Enable storage type and memory layout settings to be serialized with Vulkan graph (#2540)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/2540

## Context

Allow `api::StorageType` and `api::GPUMemoryLayout` settings to be serialized with the flatbuffer. There are two entry points for this:

1. `VkTensor` table now has two fields that can be set to select particular settings for that tensor
2. A storage type and memory layout override can be set via the `CompileSpec` API
ghstack-source-id: 219475440

Reviewed By: copyrightly, jorgep31415

Differential Revision: D55154628

fbshipit-source-id: 9d314b20ed6e3be193d61c3fd599e7ac74133512