Why rename

At this point the NameTable class stores a lot more than just name strings; it holds also refs, exit numbers, destinations, and pronunciations. Because it's then semantically confusing to do data.name_id != EMPTY_NAMEID checks (this checks that a name id's entry in the name table is 0, rather than checks that a way has no name data) (see #4642) name table and all associated classes, members, files (possibly) should be renamed.

To rename

• util::NameTable -> util::PreDatafacadeStringViewer
• NodeBasedEdgeAnnotation::NameID -> NodeBasedEdgeAnnotation::StringViewID
• name_id -> string_view_id
• EMPTY_NAMEID -> EMPTY_STRINGVIEWID

cc @daniel-j-h