[util-macros] Improve TagAwareDeserialize to read serde attributes

Summary:
Some small improvements to the TagAwareDeserialize macro:

• Verify if #[serde(remote = "Self", tag = "...")] is present
• Allow any serde tag, not necessarily "type"

Depends on D12902

Test Plan:
cargo test - Macro still works

Removing e.g. tag results in IDE (rust-analyzer) error:

Reviewers: varun, will, kamil

Reviewed By: kamil

Subscribers: ashoat, tomek

Differential Revision: https://phab.comm.dev/D12903