Do we need 2 sets of permission labels for adding comments ?

[atodorov]

From the discussion in #946

ATM it is not clear if we only need the django_comments.add_comment permission or also permissions to modify other objects because nothing checks for that on the back end.
OTOH how do I add a comment to a TestExecution if I am not allowed to change this TE? Technically these are separate tables in DB but the user experience is different.

On one hand we can modify the related object as stand alone without being able to modify the parent object, e.g. add comment, don't modify TE.

OTOH we could bind the two together and require that a user would only be able to add comments only if they can modify the parent object, e.g. check 2 permission labels.

Note: there's at least 3 places where we work with comments:

• API method TestExecution.add_comment
• UI workflow TestExecution -> add comment form
• Test case review workflow.

Not sure if there are other places where we can add comments. This is probably going to become clear once #959 and #960 are resolved.

CC @SvetlomirBalevski.