add 'button' support in custom menus

[Xelus22]

Add button support to the custom menus

the-via/reader#28 in the-via/reader is also required

Tested with Hayabusa with this configuration

"menus": [
  {
    "label": "Lighting",
    "content": [
      {
        "label": "Backlight",
        "content": [
          {
            "label": "Test Button",
            "type": "button",
            "options": [34],
            "content": [ "id_caps_lock_enable", 0, 1 ]
          }
        ]
      }
    ]
  }
],

Tested and working with
Xelus22/qmk_firmware@ca7f662