src/main: add 'rauc extract' command
src/main: add 'rauc extract' command

Allows to extract contents of a bundle to given destination folder

Signed-off-by: Enrico Jorns <a2e5f936c390f36494e46e71bcfbe365bb1e8c49@pengutronix.de>

jluebbe/rauc,jluebbe/rauc,ejoerns/rauc,jluebbe/rauc,ejoerns/rauc,rauc/rauc,rauc/rauc,rauc/rauc,ejoerns/rauc