[Core] Add Caps Word feature to core (#16588)

Co-authored-by: precondition <[email protected]>
Co-authored-by: Drashna Jaelre <[email protected]>

quantum/quantum_keycodes.h

@@ -602,6 +602,8 @@ enum quantum_keycodes {
     SECURE_UNLOCK,
     SECURE_TOGGLE,
 
+    CAPS_WORD,
+
     // Start of custom keycode range for keyboards and keymaps - always leave at the end
     SAFE_RANGE
 };
@@ -964,5 +966,6 @@ enum quantum_keycodes {
 #define PB_32 PROGRAMMABLE_BUTTON_32
 #define PROGRAMMABLE_BUTTON_MIN PROGRAMMABLE_BUTTON_1
 #define PROGRAMMABLE_BUTTON_MAX PROGRAMMABLE_BUTTON_32
+#define CAPSWRD CAPS_WORD
 
 #include "quantum_keycodes_legacy.h"