Improve display of PrimitiveIds

[GerdP]

I try to fix #10783. I want to show a popup dialog with the list of objects which were not found on the server. We already have a solution for this problem in class DownloadPrimitivesWithReferrersTask. Try for example to download objects "w2,n3,r123456789"
(w2 was redacted, n3 was deleted, r123456789 doesn't yet exist)
I could reuse this dialog after changing DownloadPrimitivesWithReferrersTask.reportProblemDialog() to public but I don't like the way how ids are reported.
Instead of "relation 123456789, way 2" I'd prefer "w2,r123456789" or "w2, r123456789".
This is the input format used in
Order probably doesn't matter, at the moment it is random because unordered collections are used to store the ids.

[GerdP]

solution with minimal impact

[GerdP]

I thought that there might be more places where collections of ids are reported but found none so far. So, I'll commit the simple patch tomorrow if nobody complains or suggests a better place to implement this.

[skyper]

Places to check are the download actions in changeset manager, see #17978, and the reverter plugin.

[skyper]

Download location, see #8946.

[GerdP]

How is #8946 related to the display of ids?

[skyper]

Replying to GerdP:

...
Order probably doesn't matter, at the moment it is random because unordered collections are used to store the ids.

How does the undelete plugin handle situations when the child object is in the list behind its parent?
Is it not better to order it by object type (nodes, ways, relations)

Replying to GerdP:

How is #8946 related to the display of ids?

The request is not related but the example is valid use case where the message should include a well formated string for undelete

[GerdP]

In 16204/josm:

fix #18979: Improve display of PrimitiveIds
Show e.g. "w2, r123456789" instead of "way 2, relation 123456789" so that output matches the expected input format for object downloads