Migrate to js_interop to make the package compatible with WASM

[GP4cK]

Summary

Support for WASM is now in stable. However, in order to use it, packages need to migrate from package:js to dart:js_interop.

Motivations

Improved performance in chromium browsers.

[Mercy811]

Hi @GP4cK, thanks for choosing Amplitude. We will take this into our plan for Flutter 4.x web. But we don't have an ETA for this now.

[percula]

Please check out this fork. I'm not the author, but have been using this fork to enable WASM and it works flawlessly. I've looked over the code changes and it all seems legit. Should be a pretty easy PR and merge to get the functionality in.

[GP4cK]

Thanks a lot! I'll try it out.