switch @0x/contract-wrappers to generated wrappers (#2037)

* switch @0x/contract-wrappers to generated wrappers

- remove TransactionEncoder
- move TokenUtils to @0x/dev-utils
- detailed changes in #2040

contracts/exchange-forwarder/package.json

@@ -47,7 +47,6 @@
     "homepage": "https://github.com/0xProject/0x-monorepo/contracts/extensions/README.md",
     "devDependencies": {
         "@0x/abi-gen": "^3.1.2",
-        "@0x/contract-wrappers": "^10.1.0",
         "@0x/contracts-gen": "^1.0.12",
         "@0x/contracts-test-utils": "^3.1.12",
         "@0x/dev-utils": "^2.2.6",