- models.AllowedFrontendURL: empty, or an absolute http(s) URL with a host
and without whitespace, control characters, a double quote, <, > or &
- classes.Rewrite leaves the document unchanged for a refused value,
inserts through EscapeText/EscapeAttr and keeps a loc or href that would
not stay an http(s) URL
- TestRewriteUnsafeFrontendURL, TestAllowedFrontendURL and a stored-row
check in TestSitemapImportSmoke