Display real fedimint block finality delay

The fedimint on-chain receive description is hard-coded to say "10 block confirmations":

https://github.com/HarborWallet/harbor/blob/1191c03edfb1f9b156f9947bed3940e488766d82/harbor-ui/src/routes/receive.rs#L153

While 10 blocks is the default, this block finality delay is configurable by the federation guardians. I added support for fetching the actual finality delay to the fedimint-wallet-client crate in this PR: https://github.com/fedimint/fedimint/pull/7657

Once this change lands in fedimint v0.9, let's use the new function to display the actual finality delay for a given federation.