feat(tftf): introduce handler for synchronous exceptions

Introduce a handler for synchronous exceptions (for aarch64) which
currently is treated as unhandled exception.

Also, added the capability to allow registering a custom handler by tftf
framework to allow graceful exit while doing negative tests.

Signed-off-by: Olivier Deprez <olivier.deprez@arm.com>
Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: I4d8d1f5af9951edfe8f068ce85f7d434b2ec070f
5 files changed