fix: fixed GroundOverlay and added sample

[kikoso]

Fix for the GroundOverlay Rendering Issue

Description

This PR fixes an issue where the GroundOverlay composable was added to the composition tree but failed to render on the map (#824).

Root Cause

The GroundOverlayPosition class was not a data class, meaning it lacked a value-based equals() implementation. In Compose, a new instance of GroundOverlayPosition was being created during recompositions. Because Compose couldn't identify these instances as equal, it triggered redundant updates to the underlying Google Maps SDK, leading to rendering instability that prevented the overlay from appearing

Changes

Core Fix: Converted GroundOverlayPosition to a data class in GroundOverlay.kt
.
API Enhancement: Added an update block for anchor in the GroundOverlay composable.

Sample App: Added GroundOverlayActivity.kt to demonstrate the fix and provide a "stress-test"

Verification Plan

Manual Verification

1. Run the maps-app.
2. Navigate to Map Features > Ground Overlay.
3. Verify that two overlays are visible:
   • One using stable (remembered) state.
   • One "stress-test" overlay that recreates its position on every recomposition.
4. Use the sliders to adjust transparency and bearing to ensure updates are smooth and correctly applied.

Fixes #824

[googlemaps-bot]

Code Coverage

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