Add swap hands status function (#19831)

Co-authored-by: Drashna Jaelre <drashna@live.com>

docs/feature_swap_hands.md

@@ -44,3 +44,9 @@ As an example, if a split keyboard has a single encoder per side, you can swap t
 const uint8_t PROGMEM encoder_hand_swap_config[NUM_ENCODERS] = { 1, 0 };
 #endif
 ```
+
+### Functions :id=functions
+
+| Function             | Description                                 |
+|----------------------|---------------------------------------------|
+| `is_swap_hands_on()` | Returns true if Swap-Hands is currently on. |

quantum/action.c

@@ -161,6 +161,10 @@ void set_swap_hands_state(size_t index, uint8_t *swap_state, bool on) {
     }
 }
 
+bool is_swap_hands_on(void) {
+    return swap_hands;
+}
+
 /** \brief Process Hand Swap
  *
  * FIXME: Needs documentation.

quantum/action.h

@@ -84,6 +84,13 @@ typedef uint32_t swap_state_row_t;
 #        error "MATRIX_COLS: invalid value"
 #    endif
 
+/**
+ * @brief Get the swap hands enable state
+ *
+ * @return true
+ * @return false
+ */
+bool is_swap_hands_on(void);
 void process_hand_swap(keyevent_t *record);
 #endif