Less/least order for stats

[mlomb]

Instead of a positive/negative dropdown, I think there should be a dedicated icon for changing the direction of the sort. This icon could be used elsewhere like:

• 'Messages sent by channel' to switch to showing the channels with the least messages, which could be useful for identifying stale channels that an owner may want to delete
• 'Emojis used in [text / reactions]' to switch to showing the least used emojis. This is only really useful for custom emojis, but can again be used for identifying pointless emojis that an owner may want to delete. This is especially useful since Discord servers only have a limited number of custom emoji slots, so if an owner wants to add a new one they may need to find one to replace
• 'Messages sent by author' to switch to showing the authors who have sent the least messages. This might be useful for small private servers where owners only want to keep active users. It is also useful for staff applications, as an owner could reject a user's application if they aren't active enough

Originally posted by @hopperelec in #26 (comment)

I like this idea that was proposed by @hopperelec in another issue. I have no plans to implement it myself for now, but I'll keep the issue open