implement support for 3-digit MNC with leading zeros

Add 3-digit flags and use the new RAI and LAI API from libosmocore throughout
the code base to be able to handle an MNC < 100 that has three digits (leading
zeros).

Depends: Id2240f7f518494c9df6c8bda52c0d5092f90f221 (libosmocore),
         Ib7176b1d65a03b76f41f94bc9d3293a8a07d24c6 (libosmocore)
Change-Id: I82f0016d9512ee8722a3489a3cb4b6c704a271fc
8 files changed