* chore: upgrade Go to 1.19.3
This re-runs ./generate.sh and ./checkfmt.sh to format and update
source code (this is primarily responsible for the huge diff.)
* fix: update tests to reflect sorting algorithm change
I was trying to create a Diagnostics Client in the tsdb package, but
IIRC importing `monitor` caused an import cycle of:
tsdb -> monitor -> cluster -> tsdb.
Moving Diagnostics to its own package will allow further use of
diagnostics.Client without running into import cycles.