Fix .h file formatting
Summary:
Addressing review from D12869
The review was:
- Can you add #pragma once to the top?
- Can you add line breaks before and after the namespace?
- Remove trailing line break
I don't understand what is trailing line break in this file. @ashoat can you explain please?
Test Plan: checked that native app compiles, and there are no changes to .wasm
Reviewers: ashoat, tomek, marcin
Reviewed By: ashoat, tomek
Subscribers: ashoat
Differential Revision: https://phab.comm.dev/D12966