CLOUDFLAREAPI: Adds CF_WORKER_ROUTE (#1243)

* CLOUDFLAREAPI: Adds CF_WORKER_ROUTE.

- CLOUDFLAREAPI: Initial support for CF_WORKER_ROUTE.
- Put CF_WORKER_ROUTE behind a per-domain feature-flag.
- Adds Integration Test.
- Create Cloudflare workers for tests.
- Updates documentation.

* Workaround for updateWorkerRoute causing stack overflow.

* Sets AccountID.

* Updates to latest master (Thanks @tresni!).

* Removes $CLOUDFLAREAPI_ACCOUNTNAME.

* Add alltrue() filter and -cfworkers flag

* Final workers changes

* alltrue() should be implemented like other filters.
* Update documentation.

Co-authored-by: Tom Limoncelli <tlimoncelli@stackoverflow.com>

pkg/js/parse_tests/036-dextendcf.js

@@ -5,6 +5,8 @@ D("foo.com", REG, DnsProvider(CF));
 D_EXTEND("sub.foo.com",
     A("test1.foo.com","10.2.3.1"),
     A("test2.foo.com","10.2.3.2"),
+    A("test3.foo.com","10.2.3.3"),
     CF_REDIRECT("test1.foo.com","https://goo.com/$1"),
-    CF_TEMP_REDIRECT("test2.foo.com","https://goo.com/$1")
+    CF_TEMP_REDIRECT("test2.foo.com","https://goo.com/$1"),
+    CF_WORKER_ROUTE("test3.foo.com","test-worker")
 );