cbmreco: Add monitoring for Event Building.

Add monitoring for digi trigger and event building. Here's a snapshot what the new metrics look like in Grafana:

@v.friese, I moved the event selection into the event builder via an optional argument. This made monitoring a bit clearer, because the number of events doesn't change. Also ensures the selection is included in the timers i've added.

added Online label

requested review from @v.friese

assigned to @v.friese

Dear @f.uhlig, @v.friese, @p.-a.loizeau,

you have been identified as code owner of at least one file which was changed with this merge request.

Please check the changes and approve them or request changes.

added CodeOwners label

approved this merge request

Looks very good.

added 4 commits

• 14f058f8 - 1 commit from branch computing:master
• f310813c - cbmreco: Add monitoring for Event Building.
• 2fadcf6e - Move event selection into event builder. Add time measurements to trigger and ev builder.
• c68d9c12 - clang-format

Compare with previous version

merged