Edk2Setup.bat: Support building platforms with Python source
Edk2Setup.bat: Support building platforms with Python source

Following the same approach as toolsetup.bat:
If build.exe, TargetTool.exe, Trim.exe or GenFds.exe is missing, run its
Python source instead.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Cinnamon Shia <7442407e887958975262eda9bcd9ed8380ec6899@hpe.com>
Reviewed-by: Liming Gao <6480311aeeb4b006862f6d13ebabddc03f51e507@intel.com>

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