feat: Add builder pattern and registry for SwapEncoders

Save swap executor addresses in a config file

src/encoding/swap_encoder/config.json

@@ -0,0 +1,6 @@
+{
+  "executors": {
+    "uniswap_v2": "0x5C2F5a71f67c01775180ADc06909288B4C329308",
+    "vm:balancer_v2": "0x543778987b293C7E8Cf0722BB2e935ba6f4068D4"
+  }
+}