Build: Convert test dir to modern cmake

Alters cmake files inside the test directory. Alters some headers
where the include paths have changed. Alter how test enablement and
disablement is handled.

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

Change-Id: Ib57e570d7265edd227c1e0712c0cee4e979e00a0
Signed-off-by: Raef Coles <raef.coles@arm.com>
88 files changed