allow custom init command

[jhernandezb]

we are currently using a fork of spm for stargaze that allows us to change the init command with a custom one (see public-awesome@ed337db) that changes some defaults like p2p settings, genesis settings, osmosis also has a custom init command for the same purpose.

Are you open to include a WithInitCmd or similar to allow a custom init command?

[ilgooz]

Contents of SPM (Starport Modules) moved under tendermint/starport by tendermint/starport#1968. Please continue your contributions there.

Thank you!