UefiPayloadPkg: Make Boot Manager Key configurable

UefiPayloadPkg: Make Boot Manager Key configurable

Provide a build option to use [Esc] instead of [F2] for devices
such as Chromebooks that don't have F-keys.

Cc: Guo Dong <guo.dong@intel.com>
Cc: Ray Ni <ray.ni@intel.com>
Cc: Maurice Ma <maurice.ma@intel.com>
Cc: Benjamin You <benjamin.you@intel.com>
Signed-off-by: Sean Rhodes <sean@starlabs.systems>
Reviewed-by: Ray Ni <ray.ni@Intel.com>
Reviewed-by: Guo Dong <guo.dong@intel.com>