feat: introduce test to generate sync EA

Introduce capability to generate Sync External Abort in TFTF.
One of the usecases of this capability is to test EL3 feature of
trapping lower ELs sync EA.

Signed-off-by: Manish Pandey <manish.pandey2@arm.com>
Change-Id: I503c6776463efdd71cb8f05f6e19fc82b8dd7fdd