A little more rigor in prefixing CALI in CMake options

[DavidPoliakoff]

I've been looking at integrating Caliper into someone else's large build. As part of that, I found myself having to set BUILD_TESTING to OFF in order to make Caliper not integrate GTest. Could you do a once-over and make that (and anything else that might not be Caliper-exclusive nomenclature) CALI_BUILD_TESTING? I worry that somebody else has BUILD_TESTING as an option that means something else, and we wind up being the source of a nasty bug.

[daboehme]

Agree that that's a good idea. Needs to be coordinated a bit, as it will require an update to the Spack package. And probably documentation.

[DavidPoliakoff]

Apparently we managed this one by just not enabling BUILD_TESTING by default