prices-xnft: change column count

[armaniferrante]

From @aarongillett: It looks like we’re using four fixed columns for the graph? I’m not sure if you’re using a library for this, and I understand these things can be a lot of work, but I was thinking we’d display different columns (vertical lines) depending on what time period is chosen. E.g. for 1W, we’d display seven columns, with Mon Tue Wed… and 1Y we’d display perhaps 4 columns