Merge remote-tracking branch 'origin/add-support-eth-pdu-sess' into integration_2026_w05 (!3769)

Add Ethernet PDU session support and make PDU session request configurable

This MR adds support for Ethernet PDU sessions, and makes PDU sessions
configurable: per-PDU session ID, type (IPv4/IPv4v6/IPv6/Ethernet [1]),
DNN, NSSAI.

Concretely, it adds a new configuration file section pdu_sessions below
uicc0 that looks like this if everything is specified (default values
are shown):

    uicc0:
      [...]
      pdu_sessions:
        - id: 1
          type: "IPv4"
          nssai_sst: 1
          nssai_sd: 0xffffff
          dnn: "oai"

It is possible to list multiple PDU sessions (add new line   - id: 2 to
request a second PDU session). It is backwards-compatible to the current
PDU session configuration (uicc0.dnn/nssai_sst/etc), the idea being that
either legacy or new configuration could be used, but (1) if
pdu_sessions exist, it will overwrite the legacy configuration, and (2)
multiple PDU sessions, and type, can only be configured using the new
config. The old parameters --extra-pdu-id and --default-pdu-id are not
accepted anymore. Documentation has been added to the UE tutorial.

It is possible to test an Ethernet PDU session [1]. It is possible to
test the PDU session inside the UE by verifying it has an TAP interface
oaitap_ue1, and ARPing the data network (arping has been added to
oai-nr-ue container for that purpose):

    ip addr add 192.168.72.140/26 dev oaitap_ue1  # same subnet as data network!
    ip link set dev oaitap_ue1 up
    arping -c 20 -I oaitap_ue1 192.168.72.135     # will send ARP request in Ethernet frame to get IP address of data network

[1] See description MR !3769 for more information. On the UE side, only
the type has to be changed to "Ethernet".

ci-scripts/conf_files/untested/episci/episci_nr-ue.nfapi.conf

@@ -12,9 +12,7 @@ uicc0 = {
 imsi = "208950000000031";
 key = "0c0a34601d4f07677303652c0462535b";
 opc= "63bfa50ee6523365ff14c1f45f88737d";
-dnn= "oai";
-nssai_sst=222;
-nssai_sd=123;
+pdu_sessions = ({ dnn = "oai"; nssai_sst = 222; nssai_sd = 123; });
 }
 
 MACRLCs = (

ci-scripts/conf_files/untested/episci/proxy_nr-ue.nfapi.conf

@@ -12,9 +12,7 @@ uicc0 = {
 imsi = "2089900007487";
 key = "fec86ba6eb707ed08905757b1bb44b8f";
 opc= "C42449363BBAD02B66D16BC975D77CC1";
-dnn= "oai";
-nssai_sst=1;
-nssai_sd=1;
+pdu_sessions = ({ dnn = "oai"; nssai_sst = 1; nssai_sd = 1; });
 }
 
 MACRLCs = (