* Refactor the list measurements function to make use of nested queries
With a dataset of 1489 test, the ooniprobe list command went from
taking 17.27s to run, to requiring 0.17s or a 100x speed boost
See https://github.com/ooni/probe/issues/1966
* Remove dead code from actions
* Improve the tests for the ListResults function
* Add test for AnomalyCount
* Add more documentation about the merging of the test_keys