Ability to create custom file viewer

[seppestas]

Add-ons for Bitbucket cloud can register file viewer modules. These file viewers make Bitbucket send the viewed source of a file in a repository to the add-on's server, where it can be rendered into a format more suitable for human consumption, after which it is shown on Bitbuckets file explorer. A nice example of an add-on using this feature is the FileViewer add-on.

These kind of file viewers are very handy when working with repositories containing e.g CAD files or special image formats not supported by default. Having these files rendered in e.g a pull request allows for awesome improvements in collaborative workflow, especially since people dealing with these kind of files are typically not that familiar with git workflows, causing them to rely more on web UIs.

Github does not have support for custom file viewers. It would be awesome if it did.