Add alt fee token support to pcli

[hdevalence]

As described in #4320,

Change the pcli tx command so that the existing --fee-tier and a new
--fee-token parameters move to pcli tx, and apply to all subcommands
(i.e., pcli tx --fee-tier ... --fee-token gm send ...) so that TxCmd::exec
can pull the right GasPrices out of the RPC response.

This will be primarily a mechanical refactoring to make the clap arguments work. Otherwise, there will be no changes required to pcli.

Currently, the fee tier argument is appended to every pcli tx subcommand, it should be lifted to the tx command as part of this refactoring

[hdevalence]

Currently the RPC responses don't include alternative gas tokens so an initial implementation would add the flag, then use the provided denom unit to look for that gas price and error out because it's missing. That's fine, this issue is just about adding the flag.