Issue to track implementation of description templates inheritance

We have the File Templates feature, that can be setup at group or instance level and be inherited by any project within given instance or group.

We also have issue and merge request description templates that currently can only be applied at the level of the project that defines these templates in its repository.

Although these are described as different features in our docs, both are basically templates, and more than that both sources of the templates leave within the project repository, with only difference that each lives within its own folder(s).

I think it would make sense to combine file and description templates setting at the group level by reusing already existing file templates setting to define from which (single) templates repository should all the projects within the group pull both file and description templates. If the group hierarchy has multiple subgroups each of the subgroups, would be able to define its own templates repository which would add to the list to already existing templates.