bug#52973: Adding a few context-menu-mode commands

[Juri Linkov]

> I agree, but is that a real danger?  How much context that gets into
> context menu can there be for a single spot in a buffer?

I've never seen a context menu longer than about 10 items with short submenus.

> And if indeed there's a lot of useful context, we should produce
> multi-level context menus, like we do with buffer-menu.
>
> Once again: this feature makes no sense whatsoever if turning on the
> context-menu-mode doesn't activate the context menus.

More context functions have the same discoverability
as all user options with multiple choices.