feat(sensors/gps): add per-receiver GPS delay parameters (#26660)

* sensors: add per-receiver GPS delay parameters

Add SENS_GPS{0,1}_DELAY params to vehicle_gps_position, following the
same device-ID matching pattern used for antenna offsets. Each receiver
can now have its own measurement delay relative to the IMU.

The delay is applied to timestamp_sample before blending. When PPS time
correction is active it takes priority over the parameter-based delay.
When a GPS driver already provides its own timestamp_sample the
per-receiver delay is not applied on top of it.

* fix(ekf2): remove EKF2_GPS_DELAY and perform param transation

* fix(param_translation): fix GPS param migration return values

Add missing return for EKF2_GPS_POS_Z and remove incorrect return for
EKF2_GPS_DELAY (1-to-many migration should not return PARAM_MODIFIED).

* fix(sensors,ekf2): rename pps_compensation and clarify delay default

* fix(ekf2): account for SENS_GPS*_DELAY in observation buffer sizing

* fix(docs): migrate EKF2_GPS_DELAY param

ROMFS/px4fmu_common/init.d/airframes/4061_atl_mantis_edu

@@ -47,7 +47,8 @@ param set-default EKF2_BCOEF_Y 25.5
 
 param set-default EKF2_DRAG_CTRL 1
 
-param set-default EKF2_GPS_DELAY 100
+param set-default SENS_GPS0_DELAY 100
+param set-default SENS_GPS1_DELAY 100
 param set-default SENS_GPS0_OFFX 0.06
 param set-default EKF2_GPS_V_NOISE 0.5