1813: Apply highlight tags on numbers in the formatted search result output r=irevoire a=Jhnbrn90
This is my first ever Rust related PR.
As described in #1758, I've attempted to highlighting numbers correctly under the `_formatted` key.
Additionally, I added a test which should assert appropriate highlighting.
I'm open to suggestions and improvements.
Co-authored-by: John Braun <john@brn.email>