add passive staking and rewards (#3579)

* add stake stuff

* more generic

* test decode bail cases

* favor early returns

programs/stake_api/src/lib.rs

@@ -0,0 +1,17 @@
+pub mod stake_instruction;
+pub mod stake_state;
+
+use solana_sdk::pubkey::Pubkey;
+
+const STAKE_PROGRAM_ID: [u8; 32] = [
+    135, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+    0,
+];
+
+pub fn check_id(program_id: &Pubkey) -> bool {
+    program_id.as_ref() == STAKE_PROGRAM_ID
+}
+
+pub fn id() -> Pubkey {
+    Pubkey::new(&STAKE_PROGRAM_ID)
+}