Research best method to move the `start` command to the RDK

[mtsitrin]

currently the dymint node is started in the Start command which currently is part of the rollapp repo

we should research a way to make dymint node launching generalized through the RDK packagage

• [ ] RDK should import dymint commands instead of duplicate implementation
• [ ] start command should be part of the RDK
• [ ] optional: find way to abstract so rollapp_evm could use this as well (currently it have ethermint's copy of the start command)