Add APGL license and copyright notices (#212)

* Add license & copyright declarations for add-watcher.

* Add copyright declarations for cache.

* Add copyright declarations for erc20-watcher.

* Add copyright declarations for ipld-eth-client.

* Add copyright declarations for tracing-client.

* Add copyright declarations for uni-watcher.

* Add copyright declarations for solidity-mapper.

* Add copyright declarations for uni-info-watcher.

* Add copyright declarations for util.

* Add copyright declarations for lighthouse-watcher.

* Change license identifier in .sol files.

Co-authored-by: prathamesh0 <prathamesh.musale0@gmail.com>

packages/cache/src/cache.spec.ts

@@ -0,0 +1,3 @@
+//
+// Copyright 2021 Vulcanize, Inc.
+//

packages/cache/src/cache.ts

@@ -1,3 +1,7 @@
+//
+// Copyright 2021 Vulcanize, Inc.
+//
+
 import assert from 'assert';
 import canonicalStringify from 'canonical-json';
 import { ethers } from 'ethers';