**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
if (command_line->HasSwitch(service_manager::switches::kNoSandbox)) {
    const base::CommandLine::CharType* noSandboxArg =
        FILE_PATH_LITERAL("--no-sandbox");
    base::CommandLine::StringVector modified_command_line;
    for (auto& arg : command_line->argv()) {
      if (arg.compare(noSandboxArg) != 0) {
        modified_command_line.push_back(arg);
      }
    }
    command_line->InitFromArgv(modified_command_line);
  }
}
void App::EnableSandbox(mate::Arguments* args) {