Deprecate FUSD

[justinbarry]

Switch to generic fungible and deploy contracts on init.

[jribbink]

Noting here: FUSD was removed on the https://github.com/onflow/fcl-dev-wallet/tree/stable-cadence branch as it had not been updated yet so was blocking release. I think it's probably a good idea to remove this permanently though, so I don't see a need to add it back & we can even consider removing it from master tree as well.