src/service: consume keys to check for invalid ones
src/service: consume keys to check for invalid ones

We should not accept unknown keys to prevent from performing actions
not actually intended by the client.

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

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