On boards, move weight and issue count to async call

What does this MR do and why?

We discovered that the fields for weight and issue count are not performant, so chose to extract them and make another asynchronous call for them. Eventually, we will more than likely move state management for boards to Apollo, so decided that we can go ahead and use this as the first Apollo feature.

Screenshots or screen recordings

How to set up and validate locally

Visit any project or group board.

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