ShellPkg/ShellCommandLib: Update DumpHex to print {|}~

ASCII characters {|}~ should be printed by DumpHex. The problem is that
if you have a string like

    {xizzy}~{foo|bar}~{quux}

in the dumped data, it will not appear as such in the *-delimited ASCII
column to the right, but as

    .xizzy...foo.bar...quux.

which is less than ideal.

Most of the commit message was inspired by/shamelessly stolen from
Laszlo's example:

    https://lists.01.org/pipermail/edk2-devel/2017-April/010266.html

Cc: Jaben Carsey <jaben.carsey@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jeff Westfahl <jeff.westfahl@ni.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Ruiyu Ni <ruiyu.ni@intel.com>
(cherry picked from commit 4bf3b994e8)

ShellPkg/Library/UefiShellCommandLib/UefiShellCommandLib.c

@@ -1745,7 +1745,7 @@ DumpHex (
       Val[Index * 3 + 0]  = Hex[TempByte >> 4];
       Val[Index * 3 + 1]  = Hex[TempByte & 0xF];
       Val[Index * 3 + 2]  = (CHAR8) ((Index == 7) ? '-' : ' ');
-      Str[Index]          = (CHAR8) ((TempByte < ' ' || TempByte > 'z') ? '.' : TempByte);
+      Str[Index]          = (CHAR8) ((TempByte < ' ' || TempByte > '~') ? '.' : TempByte);
     }
 
     Val[Index * 3]  = 0;