device: support for mutable devices

Add support for mutable devices. Mutable devices are those which
can be modified after declaration, in-place, in kernel mode.

In order for a device to be mutable, the following must be true

  * `CONFIG_DEVICE_MUTABLE` must be y-selected
  * the Devicetree bindings for the device must include
    `mutable.yaml`
  * the Devicetree node must include the `zephyr,mutable` property

Signed-off-by: Christopher Friedt <cfriedt@meta.com>