drivers: espi: npcx: Add config to disable auto-ack and use callback

Added configuration option to disable auto acknowledgment for
virtual wire WARN signals and added a callback to handle them.

This change introduces:

1. Support to disable automatic acknowledgment for VW WARN signals.
2. A callback mechanism to notify application firmware for explicit
handling.

Behavior:

1. If auto-ack is disabled, the callback notifies the application to
handle VW WARN signals.
2. If auto-ack is enabled, the driver acknowledges VW WARN signals
without notifying the application.

Signed-off-by: Yerrajennugari Raj Kumar <yerrajennugari.raj.kumar@intel.com>