bug#53255: highlight-regexp should show faces with their properties applied when selecting a face

[Juri Linkov]

>>> Like read-color shows the color names with their actual colors, the
>>> selection of a face should also show the names with their properties
>>> applied.
>>
>> The patch below implements this, but it does lead to some strange
>> effects:
>>
>> That is, some faces have odd sizes, so the completion display may look a
>> bit odd.
>>
>> But it does accurately tell you what the result is doing to be, so
>> perhaps it's OK?  Anybody have any opinions?
>
> Whereas highlight-regexp can use all faces, the preferable faces are in
> hi-lock-face-defaults, so they need to be displayed separately.

Also it would be nice to highlight faces displayed in the minibuffer
after fetching them with M-n M-n M-n ...