[invokers] Reference the parent popover/dialog

[o-t-w]

For certain UI components, like a large nested menu, for example, many buttons, each with a command and commandfor might be used.

https://codepen.io/cssgrid/pen/raBbMPL

If I try to reuse a component on the same page by copy/pasteing some HTML, needing to look through the markup and update every id and commandfor is somewhat laborious and error-prone. Both the "close" and "hide-popover" commands will very often be used to close the parent popover/dialog that the button is nested within.

It might be useful to be able to refer to the nearest ancestor popover/dialog element, rather than only being able to specify an id, which needs to be unique every time.

Something like commandfor="parent" or commandfor="nearest".

Needing to reference a unique id makes reuse awkward.