feat(core, web): migrate web to js_interop to be compatible with WASM

[Lyokone]

Description

• Migrate usage of dart:html to package:web
• Migrate usage of dart:js, dart:js_util, and package:js to dart:js_interop

Related Issues

#12027

Checklist

Before you create this PR confirm that it meets all requirements listed below by checking the relevant checkboxes ([x]).
This will ensure a smooth and quick review process. Updating the pubspec.yaml and changelogs is not required.

• I read the Contributor Guide and followed the process outlined there for submitting PRs.
• My PR includes unit or integration tests for all changed/updated/fixed behaviors (See Contributor Guide).
• All existing and new tests are passing.
• I updated/added relevant documentation (doc comments with ///).
• The analyzer (melos run analyze) does not report any problems on my PR.
• I read and followed the Flutter Style Guide.
• I signed the CLA.
• I am willing to follow-up on review comments in a timely manner.

Breaking Change

Does your PR require plugin users to manually update their apps to accommodate your change?

• Yes, this is a breaking change.
• No, this is not a breaking change.

[srujzs]

This is valid code, but I'd use an interface to make this more readable. Here's an example:

@JS()
@staticInterop
class JSError {}

extension on JSError {
  external String? get name;
  external String? get message;
  external String? get code;
} 

which would let you write simpler code like:

if (e.name == 'FirebaseError')

return r.code ?? ''

and so forth. You may not have access to extension types since that will require >=3.3, but it's even more concise with one:

extension type Error(JSObject e) {
  external String? get name;
  external String? get message;
  external String? get code;
}

[Lyokone]

Thanks I've updated this as well.
We don't have access to Dart 3.3 yet, but I'll keep in mind to revisit this once Flutter supports it

[srujzs]

Once AppJsImpl is moved to an extension type that implements JSObject, this can be JSArray<AppJsImpl>, and a cast won't be needed above, but for now this is the best alternative. :/

[srujzs]

I'm surprised this works without a toJS as this returns a JSAny? iirc. Should this be globalContext.getProperty<JSString?>('flutterfire_web_sdk_version'.toJS)?.toDart? Or perhaps more concisely, (globalContext['flutterfire_web_sdk_version'] as JSString?)?.toDart?

[Lyokone]

Good catch, surprinsinlgy, declaring it in a variable triggered an analyzer error that wasn't triggered using ??
I've updated with your version