[Keymap] Xulkal user changes (#6044)

* Xulkal user changes

Xulkal user changes

* Reduce code duplication

* Massive user code refactor

users/xulkal/custom_encoder.c

@@ -0,0 +1,13 @@
+#include "custom_encoder.h"
+
+#ifdef ENCODER_ENABLE
+const uint16_t PROGMEM encoders[][2] = {
+    { KC_PGUP, KC_PGDN },
+    { KC_DOWN, KC_UP }
+}
+
+void encoder_update_user(uint8_t index, bool clockwise)
+{
+    tap_code16(pgm_read_word(&encoders[index][clockwise]));
+}
+#endif