Bug 31633: Add holding and home data attributes to spinelabel-print.tt

Bug 31633: Add holding and home data attributes to spinelabel-print.tt

To test:

1. Apply patch
2. Have some items with call numbers and different holding/home branches.
3. Generate some quick spine labels and use your browsers dev tools to inscept the #spinelabel element. It should have 2 new data-attributes, data-homebranch and data-holdingbranch
4. You can then apply this CSS via IntraNnetUserCSS to make sure you can select these properly now:

	background: red;
}

Signed-off-by: Andrew Fuerste-Henry <andrewfh@dubcolib.org>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>