Add js-api-loader-map sample using @googlemaps/js-api-loader

[anglarett]

No description provided.

[snippet-bot]

Here is the summary of changes.

You are about to add 3 region tags.

• samples/js-api-loader-map/index.html:7, tag maps_js_api_loader_map
• samples/js-api-loader-map/index.ts:7, tag maps_js_api_loader_map
• samples/js-api-loader-map/style.css:6, tag maps_js_api_loader_map

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