feat: implement MissingDataStrategy for StackedDiscreteBar chart

[marcelgerber]

Slack discussion

Currently having it as auto (default) will hide missing data.
I'll check with the SVG tester if that seems like a good default.

Before / After

With `MissingDataStrategy.auto`	With `MissingDataStrategy.hide`

[owidbot]

Quick links (staging server):

Site	Admin	Wizard

Login: ssh owid@staging-site-stacked-discrete-bar-missing-data

• Site-screenshots: https://github.com/owid/site-screenshots/compare/stacked-discrete-bar-missing-data
• SVG tester: https://github.com/owid/owid-grapher-svgs/compare/stacked-discrete-bar-missing-data

SVG tester:

Number of differences (default views): 0 ✅
Number of differences (all views): 0 (40623d) ✅

Edited: 2024-08-15 15:48:21 UTC
Execution time: 1.24 seconds

[github-actions]

This PR has had no activity within the last two weeks. It is considered stale and will be closed in 3 days if no further activity is detected.

[marcelgerber]

Looking at the SVG diff (owid/owid-grapher-svgs@e1e16d3), almost all of these cases benefit from missing data being shown. Therefore, I will make it so that auto and show both do the same thing (show entities with missing data), and only hide hides them.

[marcelgerber]

Okay, I now tried another attempt (see owid/owid-grapher-svgs@bb88642) where with MissingDataStrategy.auto, we would remove all entities where only a single data point is available.

I thought that makes sense, but now realize in the SVG diff that this doesn't really improve any of these charts. Will revert this change, then.

[sophiamersmann]

Nice! Makes sense to me!