Ledger/transaction_logic: extract transaction_witness module to separate file

Extract the transaction_witness module from transaction_logic/mod.rs into
its own file. This is a small module containing only the TransactionWitness
struct used for transaction proofs.

Changes:
- Extract transaction_witness module to transaction_logic/transaction_witness.rs
- Use explicit imports instead of 'use super::*'
- Update mod.rs to reference the new module file

Author: dannywillems

ledger/src/scan_state/transaction_logic/mod.rs

@@ -1034,26 +1034,7 @@ impl From<&Transaction> for MinaTransactionTransactionStableV2 {
 }
 
 pub mod transaction_applied;
-pub mod transaction_witness {
-    use mina_p2p_messages::v2::MinaStateProtocolStateBodyValueStableV2;
-
-    use crate::scan_state::pending_coinbase::Stack;
-
-    use super::*;
-
-    /// <https://github.com/MinaProtocol/mina/blob/436023ba41c43a50458a551b7ef7a9ae61670b25/src/lib/transaction_witness/transaction_witness.ml#L55>
-    #[derive(Debug)]
-    pub struct TransactionWitness {
-        pub transaction: Transaction,
-        pub first_pass_ledger: SparseLedger,
-        pub second_pass_ledger: SparseLedger,
-        pub protocol_state_body: MinaStateProtocolStateBodyValueStableV2,
-        pub init_stack: Stack,
-        pub status: TransactionStatus,
-        pub block_global_slot: Slot,
-    }
-}
-
+pub mod transaction_witness;
 pub mod protocol_state {
     use mina_p2p_messages::v2::{self, MinaStateProtocolStateValueStableV2};
 

ledger/src/scan_state/transaction_logic/transaction_witness.rs

@@ -0,0 +1,18 @@
+use mina_p2p_messages::v2::MinaStateProtocolStateBodyValueStableV2;
+
+use crate::{scan_state::pending_coinbase::Stack, sparse_ledger::SparseLedger};
+
+use super::{Transaction, TransactionStatus};
+use crate::scan_state::currency::Slot;
+
+/// <https://github.com/MinaProtocol/mina/blob/436023ba41c43a50458a551b7ef7a9ae61670b25/src/lib/transaction_witness/transaction_witness.ml#L55>
+#[derive(Debug)]
+pub struct TransactionWitness {
+    pub transaction: Transaction,
+    pub first_pass_ledger: SparseLedger,
+    pub second_pass_ledger: SparseLedger,
+    pub protocol_state_body: MinaStateProtocolStateBodyValueStableV2,
+    pub init_stack: Stack,
+    pub status: TransactionStatus,
+    pub block_global_slot: Slot,
+}