Bug 24629: SIP patron items contains an array of hashes

Bug 24629: SIP patron items contains an array of hashes

$patron->{items} contains the borrowers checkouts as an array of hashes
{ barcode => $item->barcode }

When printing to log we assumed these were only barcodes

This patch pushes the current checkout as a hash and maps the values retrieved to a string

To test:
1 - Enable SIP debug mode
2 - Perform multiple checkouts for a patron
3 - Note the messages like:
    koha koha_sip_koha[13575]: ILS::Checkout: patron 123 has checked out HASH(0x55a5b187f858), HASH(0x55a5b1896ad0), HASH(0x55a5b18a6cf0), 7826832
4 - Apply patch
5 - Restart all the things
6 - Do some checkouts via SIP
6 - Messages should now have barcodes

Signed-off-by: Magnus Enger <magnus@libriotech.no>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>