Provide a JSON file with the Lint Index

Description

The thing I call the "Lint Index page" has proven to be very useful in these last couple of months. I've been using the heck out of it.

However, something that I'm missing is a way to output that information as some sort of structured format, so that one may query it or transform it into another structured format for easier utilization.

The structured format I've been working with in particular, is a spreadsheet. I built it by hand, copying the various items in the page. It took me a couple hours to do, which I'm happy to do once. But my spreadsheet will drift out of date with future releases, since I'm not going to attempt to do that work again - much less now that I've written a lot of things on top of it.

Anyway. Case in point: if I had some structured format as input, it would've taken me a few minutes to build that spreadsheet; and updating it would not be prohibitively time-consuming either! I could easily highlight diffs in new releases, and get a complete and concise list of what to change in my current work.

@GuillaumeGomez suggested a JSON file, directly downloadable from the Clippy Lints page as a possible way to achieve this :)

Additional Labels

@rustbot label +C-enhancement