FEATURE: Build example function in test area from parameters the user enters

[alwillia]

Build and display an example function in the test area based on the parameters the user enters. As the user enters parameters, the function could populate showing what it would look like; the final function could be used to fill out a documentation example, or copy/pasted in a spreadsheet directly to look at the result there.

If we ever decided to support api endpoints for testing, we could also include an example for that in this area.