SDK Integration 5/n: EventTracer (#3961)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/3961

See [design doc](https://docs.google.com/document/d/1KQ0vH0IhZK24sBbym7TYXfYssAgtPjI-htcxraoxEaM/edit).

__EventTracer__
- We integrate the SDK's `EventTracer` flow into `VulkanBackend.cpp` which is not part of `vulkan_graph_runtime`.
- Simply follow the SDK a posteriori logging flow using the durations from `QueryPool::generate_et_tracing_data()`, at the end of `VulkanBackend::execute()` inference
- Compile time gate with `ET_EVENT_TRACER_ENABLED` in this case because the dependency is not coming from Vulkan delegate itsel
ghstack-source-id: 229964244
exported-using-ghexport

Reviewed By: SS-JIA

Differential Revision: D57508095

fbshipit-source-id: 31e45cb9a12f4436d0c2406f38bf87aad707bb48