Allow jsx-pascal-case to ignore using regexps

[soundasleep]

We want to ignore a consistent theme of component naming in our project, where the offending component names match a regexp, without having to individually label each of the components, or to individually eslint-disable each of the instances.

This should be backwards compatible with existing rule sets, and matches how the camelcase rule works in eslint (which also supports regexps).

[ljharb]

I've converted this to a draft pending @soundasleep's response.