add gas-related parameters to client config

[larry0x]

Summary

gas-related parameters, namely gas, gas-adjustment, and gas-prices, should be configurable in client.toml, so that users don't need to type related flags every time they submit a tx via CLI.

see also: https://twitter.com/larry0x/status/1551761005755174912

Problem Definition

currently i have to type --gas auto --gas-adjustment 1.4 --gas-prices 0uosmo every time i submit a tx, which sucks

Proposal

#12723

[alexanderbez]

Yes, I see the point in improved UX. But there is a counter to this. A user submits a tx with gas set in their config.toml and it's not correct or a bad value, then if they forget they could end up spending hours debugging. The point I'm raising here is these are the types of values you want to be extra careful about when submitting a tx, so it's best to be explicit.

I can see both sides of the argument here...

[julienrbrt]

We've allowed to extend client.toml with default values: https://github.com/cosmos/cosmos-sdk/blob/v0.52.0-beta.1/simapp/simd/cmd/config.go#L28-L69 in 0.52 (ref #17513)

Additionally, viper will now properly bind all config value,