Add ability to ignore certain props from jsx-sort-props

[sohkai]

Useful when using React built-ins (ie. key, ref), or when you want a group of props to be together but the rest to be alphabetically sorted. For instance, I prefer having key and ref props to declared at the top before any other props, but all other props should be alphabetized.

Looking at the implementation, this looks like it should be fairly easy and I can make a PR soon, but I was wondering if there was any other feedback (maybe I missed something that already allows you to do this?).

[ljharb]

key and ref are controllable with the reservedFirst option, added in #1134.