add rdfa middleware (borrowed from findingaids) to make it easier to review embedded rdfa [#49305799]
add dependency for rdf middleware/rdflib RDFa parsing
add basic schema.org/Webpage RDFa to all site pages [#49305799]
minor cleanup on initial flat page content to enable rdflib parsing for RDFa -> RDF XML generation
update format_tei template tag to generate RDFa for names with type and ref [#49305799]
update groupsheet view, template etc. to expose information as RDFa, including tagged names in the poetry [#49305799]