program-test: Add warp tests for rent and stake rewards (#15136)

* program-test Add rent collection and stake rewards

* Improve tests to initialize vote state

* Update comment

* Update program-test/src/lib.rs

Co-authored-by: Michael Vines <mvines@gmail.com>

* Review feedback

* cargo fmt

* Avoid using hard-coded slots in tests

* Make genesis_config private

Co-authored-by: Michael Vines <mvines@gmail.com>

program-test/tests/fuzz.rs

@@ -2,12 +2,10 @@ use {
     solana_banks_client::BanksClient,
     solana_program::{
         account_info::AccountInfo, entrypoint::ProgramResult, hash::Hash, instruction::Instruction,
-        msg, pubkey::Pubkey, rent::Rent,
+        msg, pubkey::Pubkey, rent::Rent, system_instruction,
     },
     solana_program_test::{processor, ProgramTest},
-    solana_sdk::{
-        signature::Keypair, signature::Signer, system_instruction, transaction::Transaction,
-    },
+    solana_sdk::{signature::Keypair, signature::Signer, transaction::Transaction},
 };
 
 #[allow(clippy::unnecessary_wraps)]