selftest/runtime-test.py: Add test for import test from other layers
There are some features in testimage/testexport that are not tested;
this might lead to break some of these features without notice.
This adds a new test in order to test two features of testimage:
- Import test from other layers.
- Install/Unistall in the DUT without a package manager.
[YOCTO #9764]
[YOCTO #9766]
Signed-off-by: Mariano Lopez <mariano.lopez@linux.intel.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
