Adding Spring Data Rest Controllers Support and Generics

[mpmartins]

I'm sure this needs more eyes, but I decided to hack a few changes to get past the issue with generating docs for endpoints that use generics.

Also, I added support to generate documents for Spring Data Rest Controllers.

@kongchen, I'm not sure if you are interested in maintaining this repository, but I can make this solution more clean if needed.
Our team will eventually end up moving into spring-doc.

[mpmartins]

Linking #589 and #595.
Again, this is not a perfect solution. If you want to use it, please use it at your own risk.

BTW, I had to bypass the unit tests to generate a new version of the plugin.