Build: Convert cmake dir to modern cmake

Remove unneeded cmake files inside the cmake directory. Add some new
utility files.

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: I07dfb1c1e8f8346ae10e7cd891df700e5dd0d827
Signed-off-by: Raef Coles <raef.coles@arm.com>
42 files changed