feat: Allow for token_in_already_in_router

--- don't change below this line ---
ENG-4446 Took 31 minutes


Took 26 seconds

src/encoding/evm/encoder_builders.rs

@@ -21,6 +21,7 @@ pub struct TychoRouterEncoderBuilder {
     chain: Option<Chain>,
     executors_file_path: Option<String>,
     router_address: Option<Bytes>,
+    token_in_already_in_router: Option<bool>,
 }
 
 impl Default for TychoRouterEncoderBuilder {
@@ -36,6 +37,7 @@ impl TychoRouterEncoderBuilder {
             chain: None,
             executors_file_path: None,
             router_address: None,
+            token_in_already_in_router: None,
         }
     }
     pub fn chain(mut self, chain: TychoCommonChain) -> Self {
@@ -62,6 +64,16 @@ impl TychoRouterEncoderBuilder {
         self
     }
 
+    // Sets the `token_in_already_in_router` flag.
+    // If set to true, the encoder will assume that the token in is already in the router.
+    // WARNING: this is an advanced feature and should be used with caution. Make sure you have
+    // checks to make sure that your tokens won't be lost. The Router is not considered safe to hold
+    // tokens, so if this is not done within the same transaction you will lose your tokens.
+    pub fn token_in_already_in_router(mut self, token_in_already_in_router: bool) -> Self {
+        self.token_in_already_in_router = Some(token_in_already_in_router);
+        self
+    }
+
     /// Builds the `TychoRouterEncoder` instance using the configured chain.
     /// Returns an error if either the chain has not been set.
     pub fn build(self) -> Result<Box<dyn TychoEncoder>, EncodingError> {
@@ -88,6 +100,8 @@ impl TychoRouterEncoderBuilder {
                 swap_encoder_registry,
                 self.swapper_pk,
                 tycho_router_address,
+                self.token_in_already_in_router
+                    .unwrap_or(false),
             )?))
         } else {
             Err(EncodingError::FatalError(