match files between audio + ELAN + metadata

[dasch124]

• remove old TEI files
• audio filename should match ELAN / TEI file name
• each ELAN file should correspond to exactly one line in the Excel metadata spreadsheet

[dasch124]

Update 2024-02-15: There will be several texts (= lines in Metadata spreadsheet) that reference one large audio file. We need to make sure whether the conversion script looks for the filename in the spreadsheet or "guesses" it from the ELAN file name.