Fall back to the configured style when a vector tile feature lacks the property

[slesaad]

Related: #341

Problem

deck.gl's MVTLayer defaults to binary: true. In that format a numeric feature property is not stored per feature — it is hoisted into a tile-wide typed array covering every feature in the tile, allocated zero-filled and written only for the features that actually carry the key. deck then merges that array into the object it hands every style accessor, unconditionally.

The result is that a feature which never carried the property is indistinguishable from one carrying 0. From @deck.gl/layers/dist/geojson-layer/geojson-binary.js:

const feature = { properties: { ...data.properties[propertiesIndex] } };
for (const prop in data.numericProps) {
    feature.properties[prop] = data.numericProps[prop].value[numericPropsIndex];
}

So the six per-feature style fields #341 added to vector tile layers silently misbehave for any feature missing the named property:

• weightProp resolves to line width 0 — the feature draws invisibly
• radiusProp resolves to radius 0 — the point disappears
• the opacity and colour props resolve against 0 rather than falling back to the configured value

This only bites when at least one feature in the tile carries the property; if none do, the typed array is never created and the fallback works correctly. That is why it went unnoticed — a tileset where every feature carries the field behaves perfectly.

Change

resolveStyleAccessors now reports whether anything it built actually reads a feature property, and the vector tile layer decodes tiles as GeoJSON when so:

binary: !readsFeatureProperties

In GeoJSON form an absent key is genuinely absent, so the existing undefined fallbacks work as written. Layers with no *Prop configured keep the binary fast path untouched. It sits ahead of the nativeOptions spread, so a mission can still override it.

binary: false is a first-class path in this deck.gl version, not a corner: getPickingInfo's binary branch exists only to rebuild via binaryToGeojson what GeoJSON already has, getHighlightedObjectIndex carries both branches, and deck itself forces binary: false under GlobeView.

Cost

Tiles for layers that use per-feature styling are parsed to GeoJSON rather than binary, which is slower and heavier per tile. It is scoped to the layers that need it, but a dense tileset with per-feature styling will be measurably heavier than one without. The alternative is drawing the wrong thing.

Verified

Unit tests cover each of the six props individually, that a layer with none of them keeps binary decoding, and that nativeOptions can still override. Reverting the one-line predicate fails them.

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