Fix #1350, Handling the dart uri parser's problem(cannot parse uri including ':')

[Woojin-Crive]

Connection with issue(s)

Resolve issue #1350

Purpose

Adding onShouldOverrideUrlLoadingFailedToParseUri to handle the dart uri parser's problem(cannot parse uri including ':').

Example

I made a method channel and passed the original url to native.
kotlin, swift will handle the original url when the exception is raied.

InAppWebView(
    onShouldOverrideUrlLoadingFailedToParseUri: (controller, url) async {
      if (Platform.isAndroid) {
        await AndroidMethod.onShouldOverrideUrlLoadingFailedToParseUri(url: url);
        return;
      }
      if (Platform.isIOS) {
        await IosMethod.UIApplicationSharedOpen(url: url);
        return;
      }
    },
    shouldOverrideUrlLoading: (controller, navigationAction) async {
      Uri uri = navigationAction.request.url!;
      
      if (uri.scheme.toLowerCase() == "shouldOverrideUrlLoading") {
        return NavigationActionPolicy.CANCEL;
      }
      ....
    },
)

[pichillilorenzo]

Thanks for trying to solve that issue but this kind of pull request seems a workaround instead of a solution.
I'm already working on a solution that, unfortunately, would require updating the plugin to version 6.x.x (it should be available with the next version 6.0.0-beta.10)!

What I'm doing now is creating a new class called WebUri that implements Uri dart interface but also maintains the raw string value in case an issue like this happens, so the raw string value could be used as a fallback value.

Also, WebUri still be considered a Uri.

This is a big breaking change so, I can't add it to version 5.x.x.

This is a preview:

class WebUri implements Uri {
  // ...

  WebUri(String source, {this.forceToStringRawValue = false}) {
    this._rawValue = source;
    try {
      _uri = Uri.parse(this._rawValue);
      this._isValidUri = true;
    } catch (e, stacktrace) {
      print(e);
      print(stacktrace);
    }
  }

  // ...
}

// InAppWebView example
InAppWebView(
  initialUrlRequest:
    URLRequest(url: WebUri('https://flutter.dev'))
)

// example of letter case difference
final uri = WebUri('scheme://customHostValue', forceToStringRawValue: false);
print(uri.rawValue); // scheme://customHostValue
print(uri.isValidUri); // true
print(uri.uriValue.toString()); // scheme://customhostvalue
print(uri.toString()); // scheme://customhostvalue

uri.forceToStringRawValue = true;
print(uri.toString()); // scheme://customHostValue

// example of a not valid URI
// Uncaught Error: FormatException: Invalid port (at character 14)
final invalidUri = WebUri('intent://not:valid_uri');
print(invalidUri.rawValue); // intent://not:valid_uri
print(invalidUri.isValidUri); // false
print(invalidUri.uriValue.toString()); // ''
print(invalidUri.toString()); // intent://not:valid_uri