chore: Rename encoder to strategy/swap_encoder

This was confusing me when I had all of them open at the same time. Better to be extra explicit

--- don't change below this line ---
ENG-4081 Took 2 minutes

src/encoding/evm/strategy_encoder/mod.rs

@@ -1,2 +1,2 @@
-mod encoder;
-mod selector;
+mod strategy_encoders;
+mod strategy_selector;