Unifies ThisInvokeContext and dyn trait InvokeContext. (#21563)

programs/vote/src/vote_instruction.rs

@@ -310,7 +310,7 @@ fn verify_rent_exemption(
 pub fn process_instruction(
     first_instruction_account: usize,
     data: &[u8],
-    invoke_context: &mut dyn InvokeContext,
+    invoke_context: &mut InvokeContext,
 ) -> Result<(), InstructionError> {
     let keyed_accounts = invoke_context.get_keyed_accounts()?;