MdeModulePkg: Skip registering BootManagerMenu if absent

MdeModulePkg: Skip registering BootManagerMenu if absent

This is a enhancement to support the case when platform firmware
doesn't support Boot Manager Menu. For now, if BootManagerMenu FFS
can not be retrieved from FV, BDS core code will still register a
boot option for it. Then, this non-functional boot option will
still be booted by user's request (like HotKey or Exit from shell)
to cause additional boot time and error status code reported.
Therefore, it would be good to skip BootManagerMenu boot option
registration and then return error status and Invalid BootOption
data for this case so that the BootManagerBoot() or other consumers
can directly return without doing anything.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Sunny Wang <sunnywang@hpe.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>