This commit adds Xn and N2 handover procedures to the Home-Routed Roaming code.
Direct forwarding is now fully operational.
Indirect forwarding for N2 handovers is not yet supported.
To preserve the GTP-U header and extension header (even without QER)
along the source gNB -> V-UPF -> target gNB path, future work will create
PDRs without Outer Header Removal IE and FARs without Outer Header Creation IE
and implement the necessary UPF logic.
* [AMF/MME] UEContextReleaseCommand in Integrity (#2786)
Modified not to send UEContextReleaseCommand in Integrity Unprotected
NAS message such like Registration or Service request.
* [AMF/MME] UEContextReleaseCommand after Interity Protected (#2786)
Modified not to send UEContextReleaseCommand in Integrity Unprotected
NAS message such like Registration or Service request.
