osmo-auc-gen: umts: add --ind arg

During UMTS AKA, the caller typically indicates which IND slot the next used
SQN should belong to. Without this option, osmo-auc-gen will always produce SQN
from IND-slot 0. Add --ind option.

Enhance the osmo-auc-gen_test.sh to expect errors with useful printouts on
stderr, and add tests that verify valid --ind ranges.

Related: OS#2465
Change-Id: Ib60eec80d58ca9a0a01e7fbd2bcbbd4339b1a6d8
diff --git a/tests/osmo-auc-gen/osmo-auc-gen_test.err b/tests/osmo-auc-gen/osmo-auc-gen_test.err
index e69de29..46ecf2e 100644
--- a/tests/osmo-auc-gen/osmo-auc-gen_test.err
+++ b/tests/osmo-auc-gen/osmo-auc-gen_test.err
@@ -0,0 +1,9 @@
+expecting error:
+> osmo-auc-gen -3 -a milenage -r 39fa2f4e3d523d8619a73b4f65c3e14d -k EB215756028D60E3275E613320AEC880 -o FB2A3D1B360F599ABAB99DB8669F8308 -A 979498b1f72d3e28c59fa2e72f9c --ind -1
+Requested --ind 4294967295 is too large for IND bitlen of 5
+expecting error:
+> osmo-auc-gen -3 -a milenage -r 39fa2f4e3d523d8619a73b4f65c3e14d -k EB215756028D60E3275E613320AEC880 -o FB2A3D1B360F599ABAB99DB8669F8308 -A 979498b1f72d3e28c59fa2e72f9c --ind 32
+Requested --ind 32 is too large for IND bitlen of 5
+expecting error:
+> osmo-auc-gen -3 -a milenage -r 39fa2f4e3d523d8619a73b4f65c3e14d -k EB215756028D60E3275E613320AEC880 -o FB2A3D1B360F599ABAB99DB8669F8308 -A 979498b1f72d3e28c59fa2e72f9c --ind 42
+Requested --ind 42 is too large for IND bitlen of 5