Convert Encoder callbacks to be boolean functions (#12805)

Co-authored-by: James Young <18669334+noroadsleft@users.noreply.github.com>

keyboards/montsinger/rebound/rev4/keymaps/rossman360/keymap.c

@@ -55,7 +55,7 @@ const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
   )
 };
 
-void encoder_update_user(uint8_t index, bool clockwise) {
+bool encoder_update_user(uint8_t index, bool clockwise) {
    switch(get_highest_layer(layer_state)){
 case _BASE:
     if (clockwise) {
@@ -80,6 +80,7 @@ case _DEL:
     }
    break;
 }
+    return true;
 }
 
 #ifdef OLED_DRIVER_ENABLE