**Is your feature request related to a problem? Please describe.**

Currently, the only way to show the About panel on macOS is by creating a `{role: 'about'}` menu item and click it. I need to be able to show it manually.

**Describe the solution you'd like**

Electron already has the method, so it's just about exposing this to JS and documenting it:

https://github.com/electron/electron/blob/8ba271efba691357ab1970c1a553b4e019125574/atom/browser/browser_mac.mm#L376

Would also be useful to be able to pass in the panel options directly to the method to override the defaults.

I would call the method: `app.showAboutPanel(options)`

**Describe alternatives you've considered**

None.
atom/browser/api/atom_api_app.cc
Emit("gpu-process-crashed",
       status == base::TERMINATION_STATUS_PROCESS_WAS_KILLED);
}
void App::BrowserChildProcessLaunchedAndConnected(
    const content::ChildProcessData& data) {
  ChildProcessLaunched(data.process_type, data.handle);
}
void App::BrowserChildProcessHostDisconnected(
    const content::ChildProcessData& data) {
  ChildProcessDisconnected(base::GetProcId(data.handle));
}
void App::BrowserChildProcessCrashed(
    const content::ChildProcessData& data,
    const content::ChildProcessTerminationInfo& info) {
  ChildProcessDisconnected(base::GetProcId(data.handle));
}
void App::BrowserChildProcessKilled(
    const content::ChildProcessData& data,
    const content::ChildProcessTerminationInfo& info) {
  ChildProcessDisconnected(base::GetProcId(data.handle));
}
void App::RenderProcessReady(content::RenderProcessHost* host) {