Tracking issue: scatterplot improvements

[larsyencken]

What

We have a number of requests from, including some from @maxroser, for making scatterplots better:

• [x] They should explain what the bubble size is https://github.com/owid/owid-grapher/issues/1089
• [ ] They should not label non-countries with ‘no data’ in the legend https://github.com/owid/owid-grapher/issues/1167
• [ ] They should not always show all countries; it should be possible for the user to exclude data from scatter plots (three states: highlighted, shown, hidden)
• [ ] They should have a y-axis label that is horizontal so that it is possible to add more text there.
  • One reason for this is that the FASTT system we are building – where each metric has a subtitle – does not work for our current scatter plots cause they have one subtitle for both metrics.
  • To solve this, scatter plots should be designed like this –– i.e. they should not have one long subtitle referring to both metrics, but instead have two places where the two metrics can be explained. This will make it possible to manage to scatter plots via the FASTT system we are building.
• [ ] The X and Y values for a point should be easier to read on hover (currently panel on bottom right changes, in very small font)
• [ ] #1690
• [ ] #1691
• [ ] https://github.com/owid/owid-grapher/issues/1686

[larsyencken]

There were also some earlier ideas: https://www.notion.so/owid/Trajectory-scatter-improvements-d7e69137d8264f56b4010d9963778844

[danyx23]

Closing this issue as most of the sub-items have been fixed and we have follow-up issues for the remaining ones