Add list of tags to /v3/api/labelClusters API

[misaugstad]

We should include some sort of tag list in the /v3/api/labelClusters API. There is some question as to what the best method is for this (one option is to include counts for each tag, summed over the the labels that make up the cluster). But we can start with the easiest option, which is to just include every tag that's included in any of the labels that make up the cluster.

[jonfroehlich]

Nice idea. I like including counts. Would seem weird without it imo given that we have the data, easy to include, and it's important for "weighing" the information.

Downside: does slightly complicate the use of the API. But if you're using the API, you're either a coder or a vibe coder and can deal with it!

[misaugstad]

And when using includeRawLabels=true, we're not including them in the CSV output (due to them being nested). But we should at least include a list of the label_ids at that point

[misaugstad]

Aaand it looks like when using includeRawLabels=true, the raw labels aren't being included in the Shapefile or GeoPackage output!

[jonfroehlich]

Oopsies. Sorry about that. We should definitely have better test harnesses for all this stuff.