GitHub Action to add supported package list to README

[from2001]

Instead of managing them manually, it's better to implement a GitHub action to show supported package list on README.

• Read manifest.json to get a version number of com.styly.package-collection-spatial-layer
• Read list of package.json of com.styly.package-collection-spatial-layer
• Add the list to README
• Also add PolySpatial version

Dependency package list of the package can be retrieved from https://package.openupm.com/com.styly.package-collection-spatial-layer