Replace Gson with Jackson in ExoneraTor

Related to Onionoo ticket #25848 (moved) and metrics-lib ticket #26159 (moved), we should replace Gson with Jackson in ExoneraTor. For reasons, see those tickets. I'll work on this.

changed milestone to %ExoneraTor 2.1.0

added component::metrics/exonerator milestone::ExoneraTor 2.1.0 owner::karsten priority::high resolution::fixed severity::normal status::closed type::enhancement labels

Please review commit a563481 in my task-26163 branch.

The reason why I'm working on this ticket now, rather than after releasing metrics-lib and CollecTor this week, is to minimize the risk of running into things we don't like before we releasing anything.

Trac:
Status: assigned to needs_review

All fine.

Trac:
Status: needs_review to merge_ready

Merged, released, and deployed. Closing.

Trac:
Status: merge_ready to closed
Milestone: N/A to ExoneraTor 2.1.0
Resolution: N/A to fixed

closed

mentioned in issue #26178 (moved)

mentioned in issue #26230 (moved)