scripts: zephyr_flash_debug: generalize to support debugging

Replace the 'flash' method with a 'run' method, which takes a command
to run (flash, debug, or debugserver).

Rename the classes involved appropriately, and generalize the factory
interfaces as needed.

Add documentation and theory of ops.

Signed-off-by: Marti Bolivar <marti.bolivar@linaro.org>
1 file changed