Build: Split tests config from config.cmake

- Split tf-m-tests configs and PSA Arch test configs from platform
  specific config.cmake.
- Parse PSA Arch test config file if exists
- Move PSA Arch test config check to tf-m-tests

Change-Id: I80e5631fb9069ece2eed1bf6288d283f1eae25bc
Signed-off-by: David Hu <david.hu@arm.com>
15 files changed