Update all `publicationStmt/idno` URIs for the TEI document to end with ".xml" rather than "/tei"

[wlpotter]

Cf. srophe/Gaddel#199. The URIs for the TEI document will be the entity URI + ".xml", rather than the current "/tei" postfix.

We will want to update these in all data

[wlpotter]

Note to self: confirm that all xslt, etc. pipeline changes have been made first