Gdbstub test improvements: using pytest fixtures, parametrization, and
expected pattern matching on outputs from GDB and the test application.
Signed-off-by: Dmitrii Golovanov <dmitrii.golovanov@intel.com>
Clone samples/subsys/debug/gdbstub to tests and convert it back
to a build-only sample aligned with documentation.
Signed-off-by: Dmitrii Golovanov <dmitrii.golovanov@intel.com>