Programmable Button API refactor and improve docs (#18641)

quantum/keyboard.c

@@ -66,9 +66,6 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #ifdef JOYSTICK_ENABLE
 #    include "process_joystick.h"
 #endif
-#ifdef PROGRAMMABLE_BUTTON_ENABLE
-#    include "programmable_button.h"
-#endif
 #ifdef HD44780_ENABLE
 #    include "hd44780.h"
 #endif
@@ -669,10 +666,6 @@ void keyboard_task(void) {
     digitizer_task();
 #endif
 
-#ifdef PROGRAMMABLE_BUTTON_ENABLE
-    programmable_button_send();
-#endif
-
 #ifdef BLUETOOTH_ENABLE
     bluetooth_task();
 #endif