add cesiumBaseUrl option

[rot1024]

Allows you to change the name of the directory to which Cesium is copied.

This is important for the delivery of Cesium-related files to ensure that Cache-Control is properly configured and that the CDN is leveraged for high performance delivery. A hash or version number can be appended to the directory name to avoid Cache-Control problems when deploying a new version.

This feature has been tested using a demo (see cesium2, it's a different path from default):

[nshen]

Thank you very much @rot1024 . I haven't touched this project in a long time. I'd love to merge it but do you know what these errors in the CI mean?

[rot1024]

Now Node.js v16 is already EOL and the latest version of Cesium does not support node v16. It causes that error. To fix CI, it should be done in a separate PR I think.

[nshen]

Thanks @rot1024 , it seems you have been stick on reearth for very long timet. Are you working on this project full-time? Do you have any income from it?

[rot1024]

Yes I am working on Re:Earth (Eukarya Inc.) in full time. We love vite-plugin-cesium and each Re:Earth apps use it. Thanks