Add workflow for copying compiled artifacts to 0x/contract-artifacts (#1842)

The contract artifacts should remain as standard compiler output during development. Fields should only be removed/added prior to being published in `@0x/contract-artifacts`. This PR adds the `yarn transform` script to `@0x/contract-artifacts` to facilitate this. 

Going forward, `abi-gen-templates` will have to support both standard artifacts and modified artifacts if they diverge, since the templates are used for `contract-artifacts`/`abi-gen-wrappers` (modified artifact) *and* development in all the `contracts/*` packages (standard artifact).

This PR makes the following changes to `contract-artifacts`:
- remove `evm.bytecode.linkReferences` from all artifacts
- remove `evm.deployedBytecode` and `sourceTreeHashHex` from Coordinator artifact
- prettify all artifacts (whitespace only changes)

packages/abi-gen-wrappers/package.json

@@ -45,7 +45,8 @@
         "shx": "^0.2.2"
     },
     "dependencies": {
-        "@0x/base-contract": "^5.1.0"
+        "@0x/base-contract": "^5.1.0",
+        "@0x/contract-artifacts": "^1.5.1"
     },
     "publishConfig": {
         "access": "public"