license: Add support for handle INCOMPATIBLE_LICENSE in manifest creation

license: Add support for handle INCOMPATIBLE_LICENSE in manifest creation

When INCOMPATIBLE_LICENSE's is specified it need to be removed from
license.manifest and also avoid copy to target image.

Add ManifestVisitor that walk the license string searching for
INCOMPATIBLE_LICENSE's if found remove it.

[YOCTO #6765]

Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>