west: add native_sim flash, debugserver command

Add 'west flash' support which in the case of native_sim just start the
built application.
Reuse existing runner and rename it to be more generic as it does more
than just debugging now.

Also add debugserver command.

Fixes #36706

Signed-off-by: Anas Nashif <anas.nashif@intel.com>
7 files changed