implement sndev fund_nym

[huumn]

If you aren't running the payments docker compose profile, there's no way to top up the custodial wallet of a stacker for testing.

Provide a sndev fund_nym NYM in the sndev script that does something like

docker__exec db psql -U sn -d stackernews -c 'update users set msats = 1000000 where name = 'NYM''

[ekzyis]

I would also use a command that zeroes the balance so I can easier test attached wallets

[huumn]

hmmm maybe the command should be sndev set_balance NYM AMOUNT