Trying to create/import a 3rd party extension

Hi,
In my tentative of previewing AI files, I have not been able to change the list of extensions to include ai (Adobe Illustrator) files in the pdf-viewer.
I wanted then to copy the pdf-viewer extension folder, edit it in the appropriate way, then import it as a 3rd party extension. The doc I found about extension development mentions a structure different from what we can see for available extensions (in pdf-viewer for instance, there is no bower.json file which is marked as mandatory).
So how can I make an archive of one of the pdf-viewer edited to support ai files to be able to import it as 3rd party extension?
Thanks.

Hi,
Is there any help I can get about extension development please?
Thanks.