Register vector tile label features first when all tiles are fetched

[PatrikSylve]

This is a follow up on #60346, where the problem is described in more detail.

Problem

When rendering a map from a vector tile service, tiles are fetched asynchronously. Once a tile is fetched, its features are registered for labeling. However, the order in which the label features are registered can change depending on the order in which tiles are fetched. This results in inconsistent labeling.

Solution

Rather than registering label features when an individual tile is fetched, tiles are stored in a map. Once all tiles have been fetched, they are registered for labeling in order by tile id.

[github-actions]

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