Build: Rename rejection list with optional list

Besides rejection list, there are some other optional lists
like valid config lists are also needed to be generated.

Rename related names to make the logic more general.

Signed-off-by: Xinyu Zhang <xinyu.zhang@arm.com>
Change-Id: Ieafb4c0afcb8624436b23fa6c38a2858c9256aea
1 file changed