feat: Add transferFromNeeded to non permit2 methods

This will block an attempt to transfer from the user when we expect the funds to already be in the router.

chores:
- add docs
- in EncodingContext, rename transfer to transfer_type

Took 58 minutes

src/encoding/evm/strategy_encoder/transfer_optimizations.rs

@@ -35,7 +35,7 @@ impl TransferOptimization {
         }
     }
 
-    /// Returns the transfer type that should be used for the first transfer.
+    /// Returns the transfer type that should be used for the current transfer.
     pub fn get_transfers(
         &self,
         swap: SwapGroup,