feat(dRICH): merge track propagations

[c-dilks]

Briefly, what does this PR introduce?

• Add an algorithm to merge propagated tracks from dRICH aerogel and gas.
• Prefer to keep in pid algorithms, since:
  • avoid cluttering tracking algorithms
  • this is (currently) only used by PID, though it is a general algorithm for combining TrackSegments
  • it's incomplete, only combining the TrackPoints (sorting them by time); we currently don't need the other members downstream for PID
• Add CMake file for pid algorithms library
  • there are more plugin_add_* calls needed for this PR, however, they will be needed for the full set of pid algorithms, so we might as well include them now (see feat!: add IRT PID to DRICH plugin #393)

What kind of change does this PR introduce?

• Bug fix (issue #__)
• New feature (issue #__)
• Documentation update
• Other: __

Please check if this PR fulfills the following:

• Tests for the changes have been added
• Documentation has been added / updated
• Changes have been communicated to collaborators

Does this PR introduce breaking changes? What changes might users need to make to their code?

no

Does this PR change default behavior?

no

[veprbl]

Since this adds a new algorithm, would you mind adding a unit test for it? They reside in src/tests/algorithms_test.

[c-dilks]

Since this adds a new algorithm, would you mind adding a unit test for it? They reside in src/tests/algorithms_test.

Sure, will do later today.

On the other end of the testing spectrum, we have some preliminary benchmarks, which aim to test the full dRICH PID DAG.

[c-dilks]

Unit tests added.

[veprbl]

On the other end of the testing spectrum, we have some preliminary benchmarks, which aim to test the full dRICH PID DAG.

cc @wdconinc

[wdconinc]

On the other end of the testing spectrum, we have some preliminary benchmarks, which aim to test the full dRICH PID DAG.

cc @wdconinc

Ha, thanks, and email notifications from eicweb should work again now :-)

[c-dilks]

@veprbl thanks for a8aacea... seems I messed up that rebase conflict.