feat(clustering): make ClusterManager and public API open with JvmSuppressWildcards

[dkhawk]

Summary

Makes ClusterManager and its public API methods/properties open to restore subclassing and test double capabilities following the Kotlin migration. Adds @JvmSuppressWildcards annotations to generic collection arguments (addItems, removeItems, diff) for clean Java interop without wildcard variance collisions.

Changes

• Declared ClusterManager as open class ClusterManager<T : ClusterItem>
• Added open modifier to all public properties, methods, and listeners (renderer, algorithm, setAlgorithm, setAnimation, clearItems, addItem, addItems, updateItem, removeItem, removeItems, diff, cluster, onCameraIdle, onMarkerClick, onInfoWindowClick, setOnClusterClickListener, etc.)
• Added @JvmSuppressWildcards to generic collection arguments (Collection<@JvmSuppressWildcards T>) in addItems, removeItems, and diff

Reviewer

cc @LoyalAbbas

[googlemaps-bot]

Code Coverage

Overall Project	44.78% -0.02%	🍏
Files changed	0%	❌

Module	Coverage
clustering	20.33% -0.06%	❌

Files

Module	File	Coverage
clustering	ClusterManager.kt	0% -1.19%	❌

[LoyalAbbas]

LGTM

[kikoso]

Could we add some tests in ClusterManagerTest.kt?

[kikoso]

LGTM