make check: add timing information of tests

Add information to each .trs file about how long the test took to run

In the make check summary, list the 10 tests that took the longest

Perhaps keep a table of all tests run and their average test times over history In addition to long test times, report which tests took longer relative to their average running time (within a certain x%)

@houtanb Is that ticket done?

@JohannesPfeifer almost. There are some things I want to check before I close the ticket and I want to redo the graphs

Done in commits between DynareTeam/testsuite@a53bea9179ef0a524bf4aa8c89e75c49d9e5e633 and DynareTeam/testsuite@d2eb69493e07d5c04b5c437e3d424267fd01aca2