ShellPkg: Fixes for the ‘type’ command:

ShellPkg: Fixes for the ‘type’ command:
- Better handling to skip byte order mark in Unicode files.
- Only display valid ASCII characters.
- Change to use ShellPrintEx() instead of Print().
- Print each character instead of %s to avoid possible overrun when not NULL terminated.
- Check for ExecutionBreak.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Chris Phillips <chrisp@hp.com>
reviewed-by: Jaben Carsey <jaben.carsey@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@14788 6f19259b-4bc3-4df7-8a09-765794883524