Flag a Segment match instead of the entire Activity
Sometimes an activity may contain a wrongly matched segment. This can happen due to bad GPS data, or from an activity passing close from a segment (but not on it). This can have an impact on the leaderboard of the segment.
Flagging the whole activity doesn't always work because the owner of the activity may not be wiling to delete the activity it or crop it in half just to fix that segment's wrong KOM. We need to be able to remove or flag specific segment match from an activity.