feat: Updates DDS event handling examples to demo mouseover.

[willum070]

This change updates the boundaries-click and dds-datasets-polygon-click examples in the following ways:

• Updates code to track both click and mouseover events.
• Refactors each example .ts code for consistency.
• Updates the documentation region tags to reflect the new patterns.

Fixes #1589 🦕

[snippet-bot]

Here is the summary of changes.

You are about to add 3 region tags.

• samples/boundaries-click/index.ts:41, tag maps_boundaries_click_event_add_layer
• samples/dds-datasets-polygon-click/index.ts:49, tag maps_dds_datasets_polygon_click_addlistener
• samples/dds-datasets-polygon-click/index.ts:74, tag maps_dds_datasets_polygon_click_stylefunction

You are about to delete 3 region tags.

• samples/boundaries-click/index.ts:22, tag maps_boundaries_click_event_add_layer
• samples/dds-datasets-polygon-click/index.ts:24, tag maps_dds_datasets_polygon_click_stylefunction
• samples/dds-datasets-polygon-click/index.ts:67, tag maps_dds_datasets_polygon_click_addlistener

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[googlemaps-bot]

🎉 This PR is included in version 3.16.0 🎉

The release is available on GitHub release

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