Fix protomaps-leaflet (MVT) vertex limit

[nf-s]

Here we have MapboxGL on the left, and TerriaJS on the right (with protomaps version 1.19.0)

The latest version of protomaps-leaflet has fixed this issue - but we are using an older version

I believe this is the issue

• Crashing/deadlock in Safari 15 / WebKit (macOS, iOS) protomaps/protomaps-leaflet#57
• https://bugs.webkit.org/show_bug.cgi?id=230751
• There was a bug in Safari that caused crashing when drawing polygons with over 5400 vertices in a single tile
• Therefore this fix was introduced (for all browser)
• felt/protomaps.js@9d5cf55
• This was released in version 2.0.0 - see https://github.com/protomaps/protomaps-leaflet/blob/main/CHANGELOG.md#200

We are currently upgrading protomaps - but it has taken a while due to upstream deprecations.

• See Upgrade protomaps and use it for region mapping #6725
• I don't think we will have this ready in the next few months

Currently, the only workaround is to reduce the complexity of the feature by reducing the number of vertices. Sorry I am unable provide a number of the maximum number of vertices - as the limit is based on the tiling (which happens on-the-fly in TerriaJS).