Migrate features from rules.mk to DD (#23247)

keyboards/coban/pad3a/keyboard.json

@@ -14,6 +14,15 @@
             {"pin_a": "GP5", "pin_b": "GP4"}
         ]
     },
+    "features": {
+        "bootmagic": false,
+        "command": false,
+        "console": false,
+        "encoder": true,
+        "extrakey": true,
+        "mousekey": true,
+        "nkro": false
+    },
     "matrix_pins": {
         "direct": [
             ["GP8", "GP7", "GP6"]

keyboards/coban/pad3a/rules.mk

@@ -1,3 +0,0 @@
-MOUSEKEY_ENABLE = yes
-EXTRAKEY_ENABLE = yes
-ENCODER_ENABLE = yes