Extending git-hook support

Proposal

We need a way to deny binary files in the repo. This is almost possible today with the "max filesize" and "deny file-extensions" feature, but it falls short when there are more custom needs.

There are two ways to solve this as I see;

deny binary-files option

A toggle added to toggle as a push-rule. This will however still make the problem kinda ambiguous.

Expand the idea of custom hooks

A much better way imo, is to add support for custom hooks in a .gitlab/hooks/... directory. Custom hooks are possible today, but you need to change the server-files for it to work, and there are no ui for it.

Making this possible would solve the problem much broader, which I think is a good thing. There are very many custom hooks I would like to make..

Or maybe both options? One "deny binary-files" toggle for premium users, and the custom hooks directory for core :)

Other resources

This issue is also discussed in https://support.gitlab.com/hc/en-us/requests/218685