[PROPOSAL] Final design and standardization for the CLI commands and args

[cloutiertyler]

Currently there are many ways to pass arguments or environment variables in to spacetimedb CLI which differ in standalone and cloud.

e.g.

STDB_MY_VAR=foo spacetime
SPACETIME_MY_VAR=foo spacetime
SPACETIMEDB_MY_VAR=foo spacetime
spacetime --my-var foo

Also many commands need to be reviewed and potentially redesigned

[cloutiertyler]

This proposal should also specify how config files override each other and how cli args override config files.