Merge remote-tracking branch 'origin/nr_ue_multiple_rf' into integration_2026_w05 (!3593)

NR UE: add support for multiple RF frontends

This MR adds basic support for multiple RF-frontends at the UE.
There are multiple reasons why we might want this:
1. There might be different antennas needed for different bands (e.g. NTN or
   TN antennas). These antennas might be connected to different RF-frontends.
   In case of Handover, the UE needs to dynamically switch between these
   RF-frontends.
2. Each rf-simulator connection carries baseband I/Q samples. To be able to
   perform a handover between two cells at different frequencies, there must
   be two rf-simulator connections, as the baseband channels should not
   interfere and thus cannot simply be added.
3. When we want to support multiple UE simulation within one instance of
   nr-uesoftmodem, and allow multiple cells and probably even handover between
   these cells, we need either:
   1. dedicated RF-frontends for each simulated UE, or
   2. dedicated RF-frontends for each connected cell and dynamically assign
      simulated UEs accordingly.

This MR implements what is needed for 1., 2. and 3.1.

executables/nr-ru.c

@@ -570,10 +570,10 @@ static void rx_rf(RU_t *ru, int *frame, int *slot)
     rxp[i] = (void *)&ru->common.rxdata[i][get_samples_slot_timestamp(fp, *slot)];
 
   VCD_SIGNAL_DUMPER_DUMP_FUNCTION_BY_NAME(VCD_SIGNAL_DUMPER_FUNCTIONS_TRX_READ, 1);
-  openair0_timestamp old_ts = proc->timestamp_rx;
+  openair0_timestamp_t old_ts = proc->timestamp_rx;
   LOG_D(PHY,"Reading %d samples for slot %d (%p)\n", samples_per_slot, *slot, rxp[0]);
 
-  openair0_timestamp ts;
+  openair0_timestamp_t ts;
   unsigned int rxs;
   rxs = ru->rfdevice.trx_read_func(&ru->rfdevice, &ts, rxp, samples_per_slot, nb);