Support Forums: Always require a reason for reporting a topic

[Clorith]

Users reporting topics is good, having a select box for the users to choose form common reasons to report a topic is also great.

Unfortunately, it's not always possible for a moderator to know what the user making a report is thinking. If they choose the NSFW option, what did they see that they consider to be an adult theme?

Making the input box, that's generally available when the Other option is selected, always be available, and making it required at the same time, will ensure that moderators always have at least some information to go on.

This does add a hurdle when reporting a topic, but reporting a topic should require some thought, so this is not a negative, but rather a positive.

[Clorith]

In 12393:

Support Forums: Always require a reason for topic reports.

When reporting a topic, users have had the option to choose from a set of pre-determined reasons, or if none of the reasons were applicable, choosing the "other" alternative would give them a freeform text-field.

Using a pre-determined reason may leave reports short on context, where it could be down to the reporters interpretation why a reason was chosen, and would not be clear to those looking over reports.
This change addresses that by always requiring a user to not just choose a reason, but also provide context via the field asking "Why are you reporting this topic" when using the report tool in the sidebar.

Fixes #5706.