"Populated places" from "Towns" and "Settlements" layers

[trey-stafford]

Description

Combine the "Places/Towns" and "Places/Settlements" layers into one "Places/Populated places" layer. Update style to change marker-size based on population size.

In QGreenland v2, a similar layer with a population attribute was "Places/Community map (crowd-sourced)/Populated places" layer from HOTOSM. This layer gets used in some of our tutorial materials, including our QGreenland Beginner's Tutorial Series, Session 5: Processing Toolbox and Data Analysis YouTube video.

We removed all of the HOTOSM layers due to feedback indicating numerous inaccuracies. See https://github.com/nsidc/qgreenland/pull/540.

This PR provides a suitable replacement layer for our tutorial materials. Although this layer will be in the root of the "Places" group instead of the "Community map (crowd-sourced)" subgroup (as indicated in the YouTube tutorial), the user experience of selecting a layer called "Populated places" in Processing Toolbox tools will be the same.

A couple of things to consider to make this dataset more consistent with the original "Populated places" layer:

• Rename the "Population 2016" field to "population"? This would be consistent with the original layer, but we lose information about when the population data is valid for. This could be included in the layer description, but I lean toward keeping it as-is ("Population 2016"). Another option would be to duplicate the column as "population", but that could also lead to confusion.
• Filter out places with a population of 0. This would address most of our "Noted data issues" in the layer description. Also, these places are by definition without a population, so having them be a part of a layer called "Populated places" may not make sense anyway. Is there value in keeping these records? Putting them into a different layer?

Checklist

If an item on this list is done or not needed, simply check it with [x].

• [x] Config lockfile updated (inv config.export > qgreenland/config/cfg-lock.json)
• [x] Version bumped if needed (bumpversion (major|minor|patch|prerelease|build)
• [x] CHANGELOG.md updated
• [x] Documentation updated if needed
• [x] New unit tests if needed

[MattF-NSIDC]

I suppose that's a huge downside of tutorials on YouTube. By their in-depth nature, tutorials are easy to break with minor changes...

Maybe our practice should be to update the descriptions of those videos with a full list of changes? Perhaps we could also edit the video to add an initial splash screen that explains that the tutorial needs adjustments (found in video description) to work with new versions of QGreenland.