Split signature throughput tracking out of FeeCalculator (#8447)

* SDK: Split new `FeeRateGovernor` out of `FeeCalculator`

Leaving `FeeCalculator` to *only* calculate transaction fees

* Replace `FeeCalculator` with `FeeRateGovernor` as appropriate

* Expose recent `FeeRateGovernor` to clients

* Move `burn()` back into `FeeCalculator`

Appease BPF tests

* Revert "Move `burn()` back into `FeeCalculator`"

This reverts commit f3035624307196722b62ff8b74c12cfcc13b1941.

* Adjust BPF `Fee` sysvar test to reflect removal of `burn()` from `FeeCalculator`

* Make `FeeRateGovernor`'s `lamports_per_signature` private

* rebase artifacts

* fmt

* Drop 'Recent'

* Drop _with_commitment variant

* Use a more portable integer for `target_signatures_per_slot`

* Add docs for `getReeRateCalculator` JSON RPC method

* Don't return `lamports_per_signature` in `getFeeRateGovernor` JSONRPC reply

client/src/rpc_client.rs

@@ -6,8 +6,8 @@ use crate::{
     rpc_request::RpcRequest,
     rpc_response::{
         Response, RpcAccount, RpcBlockhashFeeCalculator, RpcConfirmedBlock, RpcContactInfo,
-        RpcEpochInfo, RpcKeyedAccount, RpcLeaderSchedule, RpcResponse, RpcVersionInfo,
-        RpcVoteAccountStatus,
+        RpcEpochInfo, RpcFeeRateGovernor, RpcKeyedAccount, RpcLeaderSchedule, RpcResponse,
+        RpcVersionInfo, RpcVoteAccountStatus,
     },
 };
 use bincode::serialize;
@@ -18,7 +18,7 @@ use solana_sdk::{
     clock::{Slot, UnixTimestamp, DEFAULT_TICKS_PER_SECOND, DEFAULT_TICKS_PER_SLOT},
     commitment_config::CommitmentConfig,
     epoch_schedule::EpochSchedule,
-    fee_calculator::FeeCalculator,
+    fee_calculator::{FeeCalculator, FeeRateGovernor},
     hash::Hash,
     inflation::Inflation,
     pubkey::Pubkey,
@@ -804,6 +804,31 @@ impl RpcClient {
         })
     }
 
+    pub fn get_fee_rate_governor(&self) -> RpcResponse<FeeRateGovernor> {
+        let response = self
+            .client
+            .send(&RpcRequest::GetFeeRateGovernor, Value::Null, 0)
+            .map_err(|e| {
+                io::Error::new(
+                    io::ErrorKind::Other,
+                    format!("GetFeeRateGovernor request failure: {:?}", e),
+                )
+            })?;
+        let Response {
+            context,
+            value: RpcFeeRateGovernor { fee_rate_governor },
+        } = serde_json::from_value::<Response<RpcFeeRateGovernor>>(response).map_err(|e| {
+            io::Error::new(
+                io::ErrorKind::Other,
+                format!("GetFeeRateGovernor parse failure: {:?}", e),
+            )
+        })?;
+        Ok(Response {
+            context,
+            value: fee_rate_governor,
+        })
+    }
+
     pub fn get_new_blockhash(&self, blockhash: &Hash) -> io::Result<(Hash, FeeCalculator)> {
         let mut num_retries = 0;
         let start = Instant::now();