### Preflight Checklist

- [X] I have read the [Contributing Guidelines](https://github.com/electron/electron/blob/master/CONTRIBUTING.md) for this project.
- [X] I agree to follow the [Code of Conduct](https://github.com/electron/electron/blob/master/CODE_OF_CONDUCT.md) that this project adheres to.
- [X] I have searched the [issue tracker](https://www.github.com/electron/electron/issues) for a feature request that matches the one I want to file, without success.

### Problem Description

Hi,

My team is trying to support universal linking in our application. Currently, in order to receive a handoff event from the browser, the application needs to listen to `continue-activity` event which provides `type` and `userInfo`. As per the Apple documentation [here](https://developer.apple.com/library/archive/documentation/UserExperience/Conceptual/Handoff/AdoptingHandoff/AdoptingHandoff.html#//apple_ref/doc/uid/TP40014338-CH2-SW10), the browser sends the app an `NSUserActivity` object with an `activityType` value of `NSUserActivityTypeBrowsingWeb`. The `webpageURL` property contains the URL the user was visiting, while the `userInfo` dictionary is empty. 

To provide a smooth handoff our application needs to know the URL the user is navigating from. Therefore, it would be great if the `webpageURL` parameter is exposed in `continue-activity` event. 


### Proposed Solution

The `NSUserActivity` object contains the `webpageURL` property which is set during the handoff process. 
I don't have any experience with Objective C but I believe the `webpageURL` property on the `userActivity` object can be allowed to pass [here](https://github.com/electron/electron/blob/da2baabb96161ea08a15820451f9374d63b4d678/shell/browser/mac/electron_application_delegate.mm#L161) to make it accessible.
https://github.com/electron/electron/blob/da2baabb96161ea08a15820451f9374d63b4d678/shell/browser/mac/electron_application_delegate.mm#L161


### Alternatives Considered

-

### Additional Information

The application needs to know the URL from where the user is navigating to provide a customized handoff experience. 
shell/browser/api/electron_api_app.cc
.SetMethod("isAccessibilitySupportEnabled",
                 &App::IsAccessibilitySupportEnabled)
      .SetMethod("setAccessibilitySupportEnabled",
                 &App::SetAccessibilitySupportEnabled)
      .SetMethod("disableHardwareAcceleration",
                 &App::DisableHardwareAcceleration)
      .SetMethod("disableDomainBlockingFor3DAPIs",
                 &App::DisableDomainBlockingFor3DAPIs)
      .SetMethod("getFileIcon", &App::GetFileIcon)
      .SetMethod("getAppMetrics", &App::GetAppMetrics)
      .SetMethod("getGPUFeatureStatus", &App::GetGPUFeatureStatus)
      .SetMethod("getGPUInfo", &App::GetGPUInfo)
#if defined(MAS_BUILD)
      .SetMethod("startAccessingSecurityScopedResource",
                 &App::StartAccessingSecurityScopedResource)
#endif
#if defined(OS_MAC)
      .SetProperty("dock", &App::GetDockAPI)
      .SetProperty("runningUnderRosettaTranslation",
                   &App::IsRunningUnderRosettaTranslation)
#endif
#if defined(OS_MAC) || defined(OS_WIN)
      .SetProperty("runningUnderARM64Translation",
                   &App::IsRunningUnderARM64Translation)
#endif
      .SetProperty("userAgentFallback", &App::GetUserAgentFallback,
                   &App::SetUserAgentFallback)
      .SetMethod("enableSandbox", &App::EnableSandbox);
}
const char* App::GetTypeName() {