* Add fallible send methods, and rpc_client helper
* Add helper to return RpcClient url
* Implement BenchTpsClient for TpuClient
* Add cli rpc and identity handling
* Handle different kinds of clients in main, use TpuClient
* Add tpu_client integration test
We have too many ways of sending transactions, and too many
reimplementations of the same logic all over the place.
The program deploy logic and stake-o-matic currently make the
most use of the TPU client, so this merges their implementations into
one place to be reused by both. Yay for consolidation!