Accountsdb replication installment 2 (#19325)

This is the 2nd installment for the AccountsDb replication.

Summary of Changes

The basic google protocol buffer protocol for replicating updated slots and accounts. tonic/tokio is used for transporting the messages.

The basic framework of the client and server for replicating slots and accounts -- the persisting of accounts in the replica-side will be done at the next PR -- right now -- the accounts are streamed to the replica-node and dumped. Replication for information about Bank is also not done in this PR -- to be addressed in the next PR to limit the change size.

Functionality used by both the client and server side are encapsulated in the replica-lib crate.

There is no impact to the existing validator by default.

Tests:

Observe the confirmed slots replicated to the replica-node.
Observe the accounts for the confirmed slot are received at the replica-node side.

local-cluster/src/validator_configs.rs

@@ -12,6 +12,7 @@ pub fn safe_clone_config(config: &ValidatorConfig) -> ValidatorConfig {
         account_paths: config.account_paths.clone(),
         account_shrink_paths: config.account_shrink_paths.clone(),
         rpc_config: config.rpc_config.clone(),
+        accountsdb_repl_service_config: config.accountsdb_repl_service_config.clone(),
         rpc_addrs: config.rpc_addrs,
         pubsub_config: config.pubsub_config.clone(),
         snapshot_config: config.snapshot_config.clone(),