ShellPkg: Add '-nc' flag support in 'disconnect' command

ShellPkg: Add '-nc' flag support in 'disconnect' command

As per ECR 1416, latest UEFI Shell 2.2 specification:
Define a behavior where 'disconnect -r' will disconnect drivers
from all devices but it will reconnect all consoles.
If -nc flag is used (e.g. 'disconnect -r -nc') then disconnect drivers
from all devices and don't reconnect consoles.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Tapan Shah <tapandshah@hpe.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>