I know @shargon is going to laugh, but I need synchronous versions of Send and RpcSend to be added to RpcClient.

I explicitly don't think we should add sync versions off all the JsonRpc methods exposed by RpcClient. We want to encourage developers to use the async versions unless necessary. But we also don't want to force developers who need a sync RpcClient to implement their own from scratch.

Having only sync Send/RpcSent methods mirrors the existing design of HttpClient which exposes lower level Send and SendAsync methods, but only exposes async higher level methods like GetAsync and PostAsync.