Scatterplots with fixed x-axis year have no table values

[larsyencken]

Context

Scatterplots co-plot two variables, one on x and one on y, and they are joined on (entity, year/date). But, you can also co-plot a variable against itself, in which case it is only joined against entity and you fix the x axis to a specific year/date. This is helpful to see how a variable changes compared to a fixed moment in time.

Problem

When you fix the x-axis in a scatterplot, the table view no longer displays the data values anymore.

Examples:

• https://ourworldindata.org/income-inequality#what-is-the-link-between-economic-growth-and-inequality?tab=table
• https://ourworldindata.org/grapher/smoking-death-rate-1990-2017?tab=table
• https://ourworldindata.org/grapher/smoking-deaths-1990-2017?tab=table

[larsyencken]

Marked it as "important" since we estimate ~30 charts are affected and we thus need it to make their tables correct and useful. Estimate is 1d since we believe this is also happening late in the rendering chain, meaning it should be a simple fix.

[marcelgerber]

To-do list for myself:

• [x] Refactor DataTable.columnsWithValues() because it's way too massive
• [x] Save information about targetYear in table column
• [x] Use that targetYear, if specified
• [x] Check that displaying tolerance-induced values still works fine
• [x] Maybe display the targetYear in the data table column header, for clarity's sake?
• [x] Add a test case