feat(clustering): add incremental item diffing

[RotBolt]

Summary

• Add an optional stable key to clustering; use item equals/hashCode when no key is supplied.
• Diff additions, removals, and changed values, avoiding full refreshes when items are unchanged.
• Add unit/instrumentation coverage and a 5,000-item frequently updated demo.

Fixes #504

Validation

• :maps-compose-utils:testDebugUnitTest
• :maps-app:connectedDebugAndroidTest for GoogleMapViewClusteringTests (6/6 passed on Motorola Edge 50 Neo)
• :maps-compose-utils:lintDebug :maps-app:lintDebug
• Manually tested the 5k keyed-diff demo on Motorola Edge 50 Neo with Maps tiles loaded; observed repeated 100-item updates and the algorithm retaining 5,000 items.

Manual verification

[RotBolt]

@kikoso Please review this PR for adding clustering increamental item diff