feat(arm): add support for cca CoT

- Use the development PROTPK and SWD_ROTPK if using cca CoT.

- Define a cca CoT build flag for the platform code to provide
different implementations where needed.

- When ENABLE_RME=1, CCA CoT is selected by default on Arm
platforms if no specific CoT is specified by the user.

Signed-off-by: Lauren Wehrmeister <lauren.wehrmeister@arm.com>
Change-Id: I70ae6382334a58d3c726b89c7961663eb8571a64