UX: HTTP Request/Outgoing Webhook - simple form interface for basic JSON use cases

[I-Dont-Remember]

Follow the example of Postman, HTTPie, and many other API Request building tools and let people build their request body/headers/etc. as visual key/value pairs, rather than forcing them to hand-edit a JSON string.

This also provides an alternative for some of the JSON decoding issues we've run into with Workflow variables, since if we are pulling each key/value, we know what pieces need to be escaped rather than receiving the whole thing as one mess of a string.

⚠️ this would need to still allow the option to switch to the hand-edited version, so as to not prevent power users from doing nested JSON or more interesting objects.