Add support for git-notes in commit messages

I have git-notes in a custom namespace in my repository and would like the ability for a user or administrator to show/hide them via configuration options in some meaningful way.

The particular use-case is a conversion of an Accurev repository to Git which places meta-data about the Accurev transactions in the refs/notes/accurev notes. It would be nice if this extra information could be made visible in the web-UI as well.

I don't have time right now to help supply a patch but would like to get a discussion started as to how the UI would support a feature like this. My expectation is that there would be either a repository setting or some sort of drop-down to list all available notes in certain views on GitLab but I don't have a clear idea where to put it.