Bug 14107: Patron cards: Make barcode width and height scaling editable

Bug 14107: Patron cards: Make barcode width and height scaling editable

The size of the barcode in patron card creator was hardcoded to 1% of the card height and 80% of the card width.
This patch exposes both values in the layout editor. If no values are given, the previousely hard coded values (0.01 / 0.8) are used in order to work with existing card definitions.

To test:
- Go to Home > Tools > Patron card creator
- Export a patron card (PDF) from en existing definition
- Apply patch
- Export patron card again, compare results (should be the same)
- Go to Home > Tools > Patron card creator > Manage card layouts
- Edit the layout you use for testing and set barcode scaling values e.g. to 0.03 for height and 0.4 for widht
- Export patron card again, verify that barcode size changed

Signed-off-by: Chris Nighswonger <cnighswonger@foundations.edu>
Signed-off-by: Jonathan Druart <jonathan.druart@koha-community.org>
Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>