Can't sign up for notifications without first commenting

Context

Several GitLab community members have been complaining recently that they cannot activate notifications unless they first leave a comment. This has resulted in confusion when they saw the notifications toggle is grayed out and not working. And has resulted in frustration that the workaround is leaving a 'spammy' comment.

Problem to solve

On a public project, people need the ability to subscribe to issues so that they can monitor progress and be alerted when the issue is resolved. The problem is that when you first view an issue, you can't subscribe until you leave a comment. This is inefficient.

Proposal

Allow viewers of a public project to enable notifications without first having to interact with the issue.

Example issue:

A regular contributor to GitLab has had to leave comments like: #331693 (comment 584636388).