Made QtTesting entirely optional, only build when needed

Change-Id: I29879b312f62df308b6b503bab5dbaa875aa0a74
Make it easier to build individual applications

This adds options for each application, optionally compiles their
dependencies depending on what is built. This could be made a little
more granular in future, and I hopefully covered all combinations.

Change-Id: I587f502182f9a017b3e728eb5d10ed403ecbe896
Merge branch 'build-updates'

Change-Id: If8aa301908efa8155a6acaf56226b139f4529c82