Cli: expose last valid block height (#18620)

* Add Fees struct to client

* Add complete RpcClient::get_fees methods

* Switch cli to last_valid_block_height

client/src/rpc_response.rs

@@ -4,6 +4,7 @@ use {
     solana_sdk::{
         clock::{Epoch, Slot, UnixTimestamp},
         fee_calculator::{FeeCalculator, FeeRateGovernor},
+        hash::Hash,
         inflation::Inflation,
         transaction::{Result, TransactionError},
     },
@@ -57,6 +58,14 @@ pub struct DeprecatedRpcFees {
     pub last_valid_slot: Slot,
 }
 
+#[derive(Serialize, Deserialize, Clone, Debug)]
+#[serde(rename_all = "camelCase")]
+pub struct Fees {
+    pub blockhash: Hash,
+    pub fee_calculator: FeeCalculator,
+    pub last_valid_block_height: u64,
+}
+
 #[derive(Serialize, Deserialize, Clone, Debug)]
 #[serde(rename_all = "camelCase")]
 pub struct RpcFeeCalculator {