feat: Migrates the place-class demo.

[willum070]

Continues our ongoing migration efforts by adding the place-class demo.

[snippet-bot]

Here is the summary of changes.

You are about to add 4 region tags.

• samples/place-class/index.html:7, tag maps_place_class
• samples/place-class/index.ts:7, tag maps_place_class
• samples/place-class/index.ts:25, tag maps_place_class_fetchfields
• samples/place-class/style.css:6, tag maps_place_class

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