ShellPkg: Change MM command output during script execution

ShellPkg: Change MM command output during script execution
-	Automatically use non-interactive mode during script execution.
-	Automatically use non-interactive mode when a specific value is read (omitting this behavior was a violation of the UEFI Shell Spec)
-	Only output the value read in when reading a value in a script; this allows automated use of the MM command.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jaben Carsey <jaben.carsey@intel.com>
Reviewed-by: Chris Phillips <chrisp@hp.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14874 6f19259b-4bc3-4df7-8a09-765794883524