chore(lint): replace enforce-copyright-header rule with the native equivalent

Author: alfaproject

tools/tslint/enforceCopyrightHeaderRule.ts

@@ -4,7 +4,7 @@
     "node_modules/vrsource-tslint-rules/rules"
   ],
   "rules": {
-    "enforce-copyright-header": true,
+    "file-header": [true, "Copyright Google Inc\\."],
     "no-duplicate-imports": true,
     "no-duplicate-variable": true,
     "no-jasmine-focus": true,