BaseTools: Add ConvertMasmToNasm.py to assist with MASM to NASM conversions

This script is intended to assist with MASM to NASM syntax
conversions.

The output should be manually inspected and further adjusted as
needed, since it does not provide a perfect conversion.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>