Snippets should be able to be reported as spam

Problem to solve

Snippets can sometimes be a source of Spam on public GitLab instances. Currently there is no way to report an individual snippet as spam. To report something as spam you need to navigate to the user's profile who created the snippet and report the user as spam.

Further details

Currently there is an ability for Admins to submit a snippet as Spam, but this functionality is tied to training the spam filtering system so it should not be exposed to regular users.

Proposal

We should provide a method to report snippets as part of our normal reporting workflows. Possible enhancements are #7589 (comment 298694132)