Remove warnings, outdated templates, proxy commands to C3

[irvinebroque]

What

1. Removes the outdated directory of templates in /templates. None of these are actually up-to-date. As-needed some of this content can be added to npm create cloudflare templates that live here.
2. wrangler generate and wrangler init both just kick you over to npm create cloudflare automatically now. wrangler generate template <repository_url> behavior still works, just now via create cloudflare.
3. Removes a lot of old code