Add Flyout/Submenu in Context Menu

[Antyos]

While it's nice to have the sort buttons in the context menu, I think it's a bit of an eyesore to have almost half of my json context menu taken up by sorting:

It would be really useful to have a context menu flyout/submenu as either an option or instead. I know the extensions alefragnani/vscode-bookmarks and eamodio/vscode-gitlens integrate this capability in some of their menus.

I'm not sure how best to implement this feature. A few possibilities are:

1. Have a checkbox config to use either a submenu or have the items in the root context menu
2. Have an object config to choose which sorts are shown in the root menu and which in the submenu