refactor: init only for web, no check platform

[reslear]

no need check platform:

const platform = Capacitor.getPlatform()

if (platform === "web") {
  GoogleAuth.init();
}

only

GoogleAuth.init();

TODO:

• iOS
• Android

[joeflateau]

@reslear try this instead

    @objc(init:)
    func initSwift(_ call: CAPPluginCall) {
        call.unimplemented("Not available on iOS")
    }