Add program_ids() methods

Added CompiledInstruction::program_id() so that we don't need to pass
around instruction indexes just for Message::program_id().

Also added Message.program_ids() that returns a slice so that we
can move those pubkeys into Message::account_keys.

core/src/storage_stage.rs

@@ -402,7 +402,7 @@ impl StorageStage {
             // the storage_keys with their signatures
             for tx in entry.transactions {
                 let message = tx.message();
-                for (i, program_id) in message.program_ids.iter().enumerate() {
+                for (i, program_id) in message.program_ids().iter().enumerate() {
                     if solana_storage_api::check_id(&program_id) {
                         match deserialize(&message.instructions[i].data) {
                             Ok(StorageInstruction::SubmitMiningProof {