Add trace tags to jobs in package jobutil
Created by: tbliu98
Stacked on https://github.com/sourcegraph/sourcegraph/pull/35608 Part of #34009 (closed)
Add trace tags to jobs in package jobutil
which have fields outside of wrapping their child jobs.
Add String()
methods to types Protocol
and FlagSet
for ease of tracing them as struct fields.
Test plan
All existing jobutil
tests pass, visually verify trace output.