Bugfix refactor and improvements (#246)

* Refactor the Proxy interface so that it handles
  any response type (including JSON)
* Fix how the Proxy handles redirects and other
  non-successful status codes by avoiding to parse
  non-JSON payloads
* Improve the Proxy interface so that the query params
  don't have to be manually encoded in the `url` argument,
  by using the existing `params` argument (which was
  previously ignored)
* Add the new `emit_on_deploy` flag as an argument
  to the "deploy trigger" endpoint

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Co-authored-by: fern-api[bot] <115122769+fern-api[bot]@users.noreply.github.com>
Co-authored-by: Jay Vercellone <jay@pipedream.com>