Build: Convert app directory to modern cmake

update app cmake files. Update header includes where include paths have
changed. Add support for secure test only enablement.

WARNING: This change will not build in isolation, it requires _all_
other cmake changes to successfully build. It is split out only for ease
of understanding.

Signed-off-by: Raef Coles <raef.coles@arm.com>
Change-Id: I3e8eb83c13b5e4dbb428615ba83567f14000285b
4 files changed