* Move ConnectionCache back to solana-client, and duplicate ThinClient, TpuClient there
* Dedupe thin_client modules
* Dedupe tpu_client modules
* Move TpuClient to TpuConnectionCache
* Move ThinClient to TpuConnectionCache
* Move TpuConnection and quic/udp trait implementations back to solana-client
* Remove enum_dispatch from solana-tpu-client
* Move udp-client to its own crate
* Move quic-client to its own crate
1. Move logics related to creating endpoint, creating new connection and retry 0rtt connections into a wrapper construct QuicNewConnection to put the logic together.
2. get_or_add_connection: logic is much simplified to allow manage the connection cache -- the QUIC connection is lazy constructed. get_or_add_connection should no longer be a global hotspot.
3. Per connection stats update is moved out of get_or_add_connection to avoid bad connection impacting good connections.
Add an interface send_wire_transaction_batch_async to TpuConnection to allow for sending batches without waiting for completion
Co-authored-by: Anatoly Yakovenko <anatoly@solana.com>
* Update TpuConnection interface to be compatible with versioned txs
* Add convenience method for sending txs
* use parallel iterator to serialize transactions
* Add quic-client module to send transactions via quic, abstracted behind the TpuConnection trait (along with a legacy UDP implementation of TpuConnection) and change thin-client to use TpuConnection