Clean up and rewrite the tests in cmake

[jmcarcell]

BEGINRELEASENOTES

• Clean up and rewrite the tests in cmake. Compile all the .cpp files instead of specifying them manually. Define a function to set the environment so that adding a test is a one liner in most cases.

ENDRELEASENOTES

I would like one test = one line, currently we have way too much repetition.

[jmcarcell]

-140 lines of cmake, formatting will be left for another time; to be done centrally like with .clang-format