1768833 - Re-implement traits for internal types again

Status: NEW

(Data Platform and Tools :: Glean: SDK, enhancement, P4)

Description

[Jan-Erik Rediger [:janerik]]

We expose traits for consumers to implement if they wrap metric types, to ensure they follow the same API.

However with the move to UniFFI we stopped implementing the traits for our own types.
UDL requires us to use a specific API (no Into<Option<&str>> easily possible).

The FOG codebase uses some macros to pass around data, so we need to keep everything in sync, so switching the API needs to be done all at once.
For now we defer this work a bit.