runqueue: add ability to enforce that tasks are setscened

runqueue: add ability to enforce that tasks are setscened

Add the ability to enter a mode where only a specified whitelist of
tasks can be executed outright; everything else must be successfully
provided in the form of a setscene task (or covered by a setscene task).
Any setscene failure outside of the whitelist will cause the build to
fail immediately instead of running the real task, and any real tasks
that would execute outside of the whitelist cause an immediate build
failure when it comes to executing the runqueue as well.

The mode is enabled by setting BB_SETSCENE_ENFORCE="1", and the
whitelist is specified through BB_SETSCENE_ENFORCE_WHITELIST, consisting
of pn:taskname pairs. A single % character can be substituted for the pn
value to match any target explicitly specified on the bitbake command
line. Wildcards * and ? can also be used as per standard unix file name
matching for both pn and taskname.

Part of the implementation of [YOCTO #9367].

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>