qca: add options for head, qt5, tests, api docs and building all plugins

@mikemcquaid Do you think all of the plugins should just be `:recommended` (excepting `qca-ossl` which should always be built), since they all successfully build?
Partly person preference (I never do that, especially with CMake), but also because if you need to debug the formula, and drop into a shell, IMO it is much easier to work with if the build directory and source are separate.

Btw, the core dev has just applied the patch upstream in master.