Add default tilt sensitivity get function

Added `relay_chn_tilt_get_default_sensitivity` function and test cases.

Refs #1085 and fixes #1101

include/relay_chn.h

@@ -63,6 +63,18 @@ esp_err_t relay_chn_register_listener(relay_chn_state_listener_t listener);
  */
 void relay_chn_unregister_listener(relay_chn_state_listener_t listener);
 
+#if CONFIG_RELAY_CHN_ENABLE_TILTING
+/**
+ * @brief Get the default tilting sensitivity for the relay channel.
+ *
+ * This function retrieves the default sensitivity for the relay channel's automatic
+ * tilting mechanism.
+ *
+ * @return Sensitivity value in percentage: 0 - 100%.
+ */
+uint8_t relay_chn_tilt_get_default_sensitivity(void);
+#endif
+
 #if CONFIG_RELAY_CHN_COUNT > 1
 /**
  * @brief Get the state of the specified relay channel.