feat: Migrates the web-components-events sample to js-api-samples.

[willum070]

This PR does the following things:

• Migrates the web-components-events sample to js-api-samples.
• Updates the bootstrap loader to use the standard key and the weekly channel instead of beta.
• Cleans up type checking: Cast elements returned from document.querySelectorAll to google.maps.marker.AdvancedMarkerElement which allows safely removing inner file @ts-ignore rules.
• Removes trailing export {}.

[snippet-bot]

Here is the summary of changes.

You are about to add 3 region tags.

• samples/web-components-events/index.html:7, tag maps_web_components_events
• samples/web-components-events/index.ts:7, tag maps_web_components_events
• samples/web-components-events/style.css:6, tag maps_web_components_events

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