Items: Second Sort in Lists Should be Previous Sort Column

Thanks, Charlotte! I am rather fond of this functionality

Tested:
Filter: Books.
a) Location, with Title as second sort: http://folio-demo-test.aws.indexdata.com/items?filters=item.book&sort=location%2Ctitle
b) Barcode, with Location as second sort: http://folio-demo-test.aws.indexdata.com/items?filters=item.book&sort=barcode%2Clocation
c) Title (reversible, to get the two identical titles 'Temeraire' displayed, with barcode as second: http://folio-demo-test.aws.indexdata.com/items?filters=item.book&sort=-title%2Cbarcode
All looks good.

Tested:
No filter selected:
a) Location, with Title as second sort: http://folio-demo-test.aws.indexdata.com/items?filters=&sort=location%2Ctitle
b) Barcode, with Location as second sort: http://folio-demo-test.aws.indexdata.com/items?filters=&sort=barcode%2Clocation
c) Title (reversible, to get the two identical titles 'Temeraire' displayed, with barcode as second: http://folio-demo-test.aws.indexdata.com/items?filters=&sort=-title%2Cbarcode
All looks good.

Remarks:
Didn't test material-type ().

Fixed in https://github.com/folio-org/ui-items/commit/4701fde406e924302777a6c6e64f0aefa39c58f6

The new issue is .

This was pretty easy to do, but I thought for a long while that I'd got it wrong, because sorting by material-type has stopped working – and I used it as part of all my tests.

I'll file that as a separate issue, and finish up on this one.