Fixes #378

Generating thumbnail images with npm run create-image is broken, this appears to stem from #253 due to the change to a .ts file and the replacement of puppeteer with playwright. In this PR I revert those two changes, and make some additional improvements to the image generation script:

• Change the wait condition to rely on map.loaded() instead of network status. This solves cases where the screenshot would take before the map had loaded. An additional 1.5 second delay ensures that post-loading content (e.g. added images) are captured in the screenshot.
• Fix blurry images by calling "page.setViewport" before "page.setContent" (see blurry canvas if deviceScaleFactor > 1 puppeteer/puppeteer#2755 (comment)).
• Disable headless mode when generating a single image, this allows for interacting with the map to improve the screenshot (i.e. display the popup on click) and is also helpful for debugging.
• Add an experimental option to automate generating all images by running npm run create-image . This is currently crashing due to a puppeteer issue, but generates most of the images. Puppeteer remains in headless mode during this process.
• Refactoring for readability.

Before:

After: