Tag cloud: Improve "no content" rendering when there are no tags

[richtabor]

Like many other blocks, we should not render a "no content" message on the front end.

I propose the editor could render example tags (even tag-1, tag-2) if there are no tags.

And on the front end, don't render anything (not unlike the empty button block, or empty site description).

Current (editor)

Current (front end)

[akasunil]

I'm not sure about the examples of tags. However, text messaging has to be improved to be more specific to tag cloud block.
Also, we definitely should prevent the block from rendering on the front end if tags are not available.

[akasunil]

Duplicate issue of #63684

[richtabor]

And both mine. I'll close this one as the other is clearer. 😅