Commander: make low remaining flight time configurable and fix clearing condition (#22863)

* Commander: make low remaining flight time configurable and do not clear

- add _ACT param to disable/warning/RTL this feature
- publish rtl flight time estimate also in RTL, and thus fix re-validation
- make failure message clearer, distinguish from battery low

* battery check: add hysteresis for declaring battery_low_remaining_time false again


---------

Signed-off-by: Silvan Fuhrer <silvan@auterion.com>
Co-authored-by: KonradRudin <98741601+KonradRudin@users.noreply.github.com>

src/modules/commander/commander_params.c

@@ -1030,3 +1030,17 @@ PARAM_DEFINE_INT32(COM_THROW_EN, 0);
  * @unit m/s
  */
 PARAM_DEFINE_FLOAT(COM_THROW_SPEED, 5);
+
+/**
+ * Remaining flight time low failsafe
+ *
+ * Action the system takes when the remaining flight time is below
+ * the estimated time it takes to reach the RTL destination.
+ *
+ * @group Commander
+ * @value 0 None
+ * @value 1 Warning
+ * @value 3 Return
+ * @increment 1
+ */
+PARAM_DEFINE_INT32(COM_FLTT_LOW_ACT, 3);