toaster.bbclass: remove directory scan logic for detecting artifacts

toaster.bbclass: remove directory scan logic for detecting artifacts

toaster.bbclass does a scan of the image deploy and SDK directories
when a build finishes. However, this brings no benefit and could be
better managed and made easier to modify if moved to toasterui and
carried out when the BuildCompleted event occurs.

Remove the image scan code from toaster.bbclass, prior to moving it
to toasterui and buildinfohelper.

Also remove the license manifest update code, as this can also be
done from toasterui.

The postfuncs for do_populate_sdk are retained, but no longer
do the directory scan for SDK artifacts. Instead, they fire
an event with the value of the TOOLCHAIN_OUTPUTNAME variable,
as this is only accessible at the point when the do_populate_sdk
and do_populate_sdk_ext tasks are run. The value of this can then
be used by buildinfohelper to find the SDK artifacts produced by a
target.

[YOCTO #9002]

Signed-off-by: Elliot Smith <elliot.smith@intel.com>
Signed-off-by: bavery <brian.avery@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>