Improve ergonomics for Kotlin wrapper

[oguzkocer]

Improves a few things in the Kotlin wrapper:

• Renames WpRequestResult.WpRequestSuccess to WpRequestResult.Success
• Renames WpRequestResult.WpRequestSuccess.data to WpRequestResult.WpRequestSuccess.response because the previous data field has another data field inside, so in usage, it looked like success.data.data.
• Adds a few Kotlin extensions for ParsedUrl and in most of the API it replaces it with java.net.URL and internally converts it to ParsedUrl. I'll take a look to see if we could just lift ParsedUrl as URL in another PR.
• Publishes Kotlin source files so it's easier to work with from the clients.