Add CI test for event loader eudaq2
Added 6 tests that check for the number of pixel hits (on each of the 6 MIMOSA26 planes) read in by the
EventLoaderEUDAQ2 on a small data set (subset of run 273 from DESY, March 2019).
These tests will reveal errors related to changing the naming convention of planes or so like in !111 (merged).
The tests are recognised by cmake and run successfully on my laptop.