Add CardDav and CalDav servers (#80)

* Add CardDav and CalDav servers

This implements the servers, but not the clients (yet). The implementation is essentially a proxy to Radicale (as a container in `docker-compose.yml`), with certain security assurances.

If you're upgrading, basically you'll need to create a new `data-radicale` directory, and everything else should just work.

This will also release v2.3.0 with those enabled by default. Tested with Thunderbird and Apple Calendar + Contacts.

To disable these, simply add the new config details and comment out or don't add the new `radicale` service from `docker-compose.yml`.

Related to #56

routes/.well-known/caldav.tsx

@@ -0,0 +1,9 @@
+import { Handler } from 'fresh/server.ts';
+
+import { FreshContextState } from '/lib/types.ts';
+
+interface Data {}
+
+export const handler: Handler<Data, FreshContextState> = () => {
+  return new Response('Redirecting...', { status: 301, headers: { 'Location': '/caldav' } });
+};