saip/personalization: add MncLen configurable parameter
Add a new ConfigurableParameter that represents the MNC length
(2 or 3 digits) in EF.AD (Administrative Data).
Change-Id: I6c600faeab00ffb072acbe94c9a8b2d1397c07d3
Co-authored-by: Vadim Yanitskiy <vyanitskiy@sysmocom.de>
Jenkins: skip-card-test
