Feature #2193: write osmo-gsm-tester test cases and extend tester API
osmo-gsm-tester: add test case: smpp: transaction mode
Add test cases to test SMPP in transaction mode:
1- Send an SMS from SMPP to MS when the MS is already registered beforehand. Expected behavior: the MS should receive the SMS correctly.
2- Send an SMS from SMPP to MS before it is already registered. Expected behavior: the MS should not receive the SMS and the SMPP client should receive an error stating so.