feat: Migrates the polyline-complex sample.

[willum070]

This PR does the following things:

• Migrates the polyline-complex sample to js-api-samples.
• Refactors to use gmp-map and dynamic loading.

[snippet-bot]

Here is the summary of changes.

You are about to add 3 region tags.

• samples/polyline-complex/index.html:7, tag maps_polyline_complex
• samples/polyline-complex/index.ts:7, tag maps_polyline_complex
• samples/polyline-complex/style.css:6, tag maps_polyline_complex

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