feat(rpc-proxy): integrate puzzle auth

[friofry]

The rpc proxy supports solving the puzzle and using an ephemeral token to perform 100 requests (valid for 10 minutes).

(status-im/eth-rpc-proxy#71)

Let's use this mechanism instead of hardcoding the basic authentication credentials in the app at CI compile time.

check this go implementation: https://github.com/status-im/eth-rpc-proxy/blob/master/go-auth-service/internal/puzzle/puzzle.go