Create Endpoint, part 1: validate

[beriberikix]

• Navigate to /endpoints/new and prompt for path, method, source code and source code language
  • Ignores future configurations like certs, setting protocol, scheduled/cron jobs, etc.
• Path: Validate that path is unique in endpoints where domain matches local storage
  • This ignores future features like path wildcards - assumes fixed routes. Ex. /user/:I'd
• Methods: default to all supported methods and optionally select a subset
  • Initially only standard methods, ex not observe
  • Will need multiple src, one per method
• Source code: basic textfield
  • Form uploader & Git webhooks in the future
  • Source code won't be validated except for being non-zero length