Investigate whether we can remove the `downcastNodeToNumberIfBigint` _request_ transform

[steveluscher]

I'm not clear on what Agave's RPC will do if you give it a JSON-RPC request with a number in it that exceeds Number.MAX_SAFE_INTEGER. Will it parse it as a u64 just fine? Maybe?

Investigate whether we can remove the request transform downcastNodeToNumberIfBigint().