Revert "Rename programs to instruction_processors (#3789)" (#3824)

This reverts commit 34344982a9.

programs/exchange_api/src/lib.rs

@@ -0,0 +1,18 @@
+pub mod exchange_instruction;
+pub mod exchange_processor;
+pub mod exchange_state;
+
+use solana_sdk::pubkey::Pubkey;
+
+pub const EXCHANGE_PROGRAM_ID: [u8; 32] = [
+    134, 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() == EXCHANGE_PROGRAM_ID
+}
+
+pub fn id() -> Pubkey {
+    Pubkey::new(&EXCHANGE_PROGRAM_ID)
+}