File input docs improvements

[joeyballentine]

• Displays supported filetypes using type tags instead of in the description. Also applies automatically now instead of needing to be done via the backend
• Indicates if an input is the primary input for its type, and lets the user know what that means.

I don't necessarily like having all those booleans in InputOutputItem, but we can maybe have some kind of doc component selector thing in the future if we need to add more of those for different input types.

[joeyballentine]

going to assume this is good now. if it isn't, we can always fix it in another pr