Rpc: introduce get_inflation_reward rpc call (#16278)

* feat: introduce get_inflation_reward rpc call

* fix: style suggestions

* fix: more style changes and match how other rpc functions are defined

* feat: get reward for a single epoch

* feat: default to the most recent epoch

* fix: don't factor out get_confirmed_block

* style: introduce from impl for RpcEncodingConfigWrapper

* style: bring commitment into variable

* feat: support multiple pubkeys for get_inflation_reward

* feat: add get_inflation_reward to rpc client

* feat: return rewards in order

* fix: rename pubkeys to addresses

* docs: introduce jsonrpc docs for get_inflation_reward

* style: early return in map (not sure which is more idiomatic)

* fix: call the rpc client function args addresses as well

* fix: style

* fix: filter out only addresses we care about

* style: make this more idiomatic

* fix: change rpc client epoch to optional and include some docs edits

* feat: filter out rent rewards in get_inflation_reward

* feat: add option epoch config param to get_inflation_reward

* feat: rpc client get_inflation_reward takes epoch instead of config and some filter staking and voting rewards

client/src/rpc_request.rs

@@ -30,6 +30,7 @@ pub enum RpcRequest {
     GetIdentity,
     GetInflationGovernor,
     GetInflationRate,
+    GetInflationReward,
     GetLargestAccounts,
     GetLeaderSchedule,
     GetMaxRetransmitSlot,
@@ -91,6 +92,7 @@ impl fmt::Display for RpcRequest {
             RpcRequest::GetIdentity => "getIdentity",
             RpcRequest::GetInflationGovernor => "getInflationGovernor",
             RpcRequest::GetInflationRate => "getInflationRate",
+            RpcRequest::GetInflationReward => "getInflationReward",
             RpcRequest::GetLargestAccounts => "getLargestAccounts",
             RpcRequest::GetLeaderSchedule => "getLeaderSchedule",
             RpcRequest::GetMaxRetransmitSlot => "getMaxRetransmitSlot",