Make text_ids shared with TextFabric function as URL identifiers

[jamespstrachan]

@codykingham explained to me previously:

text_id:: A32 

This is a label that comes from an original publication. It’s important for referencing purposes (similar to the line numbers).

and now @dirkroorda has these textid fields on his end but no clear way to join them back up with the nena site:

From Dirk:

But now I discover that I do not have the information to arrive at the text identifier. I do have a feature textid in the tf data, but it gives me values like this

A4  = A Tale of a Prince and a Princess
A7  = A Man Called Čuxo
A45 = The Fox and the Stork

(all these Barwar dialect) Do these identifiers mean something to you? I think we need to add the identifiers used on the website as well (or instead).

If that works out, it would be nice if each page could show a link to the search interface (one fixed link), because user can then rapidly go back and forth between searching and listening to the audio pages.

Originally posted by @dirkroorda in https://github.com/CambridgeSemiticsLab/nena/issues/67#issuecomment-823119818

We should allow inbound links to audio pages on the basis of these textids (probably even as a replacement for the current numeric id in the url, unless we coerce both to a slugified form)

[dirkroorda]

I am completely agnostic here. Whether it is a new TF feature with the website numeric ID, or it is linking based on existing textids, all good to me. A new feature does need to be included in the tf-generation workflow of course.