Add popup for table / API anchors

Spun off https://github.com/KhronosGroup/Vulkan-Docs/issues/2670 . Asciidoc does not by default have any way to discover anchors for imbedded anchors such as found in tables and API interface blocks, or inline in paragraphs. For VUID anchors, we added some CSS that creates a floating link popup when you hover over the VUID name. Something like this should be possible for tables, although maybe trickier to recognize the patterns (see src/css/khronos.css - the rules trigger off "li > p > a[id^="VUID-"]" while table names are arbitrary IDs).