Enc/dec libs for missing 5GMM NAS Messages

OAI UE cannot en-/decode below messages: Three downlink messages:

• Registration reject: !3060 (merged)
• Authentication reject enc/dec and unit test: !3371 (merged)
• Security mode reject enc/dec and unit test: !3369 (merged)

Two uplink messages:

• Service request enc/dec and unit test: !3065 (merged)
  • Procedure implementation in stack in #900
• Service Accept enc/dec and unit test: !3247 (merged)
• Service Reject enc/dec and unit test: !3275 (merged)
• Authentication failure: !3381 (merged)