Rllmuk Topic Ignore Script - fix table striping in Forum view

Since we're hiding rows rather than removing them, it's playing havoc with the `nth-child(2n)`-based table striping.

If we remove the rows, we'd need to put them back in the same place when viewing ignored topics.

Otherwise, we could manually fix the striping the old-fashioned way, with alternating classes.

Start by locating the Rllmuk Topic Ignore Script behavior that hides rows in the Forum view and inspect how the table's nth-child(2n) striping is affected. The work is done when visible rows retain alternating striping while ignored topics can still be viewed in their original positions.

Written by the indexing model from the issue text.