[util-macros] Add tests for serde and TagAwareDeserialize behavior
Summary:
Added tests to demonstrate both serde issue described in ENG-8901 and the macro introduced in D12901
Depends on D12901
Test Plan: cargo test
Reviewers: varun, will, kamil
Reviewed By: kamil
Subscribers: ashoat, tomek
Differential Revision: https://phab.comm.dev/D12902