Exclude leaderboard filter

[AdityaHegde]

closes #879 Adding exclude filter to leaderboards.

We maintain include and exclude filter modes for each leaderboard. An icon will appear at the top right on hover.

The tooltip is updated based on what mode the leaderboard is in.

Include and exclude filters for a dimension are separated out in the pills. Exclude filters get a prefix Exclude before the name.

[magorlick]

Thank you for the great start @AdityaHegde ! Passing to @bcolloran for the design and UX work.

[bcolloran]

hey @AdityaHegde, the control+click action to exclude leaderboard items is not working for me (on linux, both chrome and firefox) -- i see the tooltip, and other control+click actions work in the app, but I that one is not working. (Sorry if this is not ready to be looked at, I see that it's still in draft but I thought I'd start to look since i got this ping)

[hamilton]

Closing this in favor of #978, which builds off of this.