Add support for OG Xbox Images

[astarivi]

The original Iso2God had support for OG Xbox images, but this feature was removed in the CLI implementation. This PR aims to restore support for XBE executables, addressing issue #13.

The implementation checks for an XEX file inside the XDVDFS image first; if not found, it then searches for an XBE file.

This is a working, but still rough, WIP implementation of the concept. If you have any thoughts or suggestions on this feature, I'd be happy to hear them.

[iliazeus]

Thank you for your contribution! I've cleaned up the code a bit, and updated the wording to reflect that the tool now also accepts OG Xbox ISOs.

One thing though - are you able to verify that the resulting files work? Preferably, both with and without the --trim option. I currently don't have access to a 360 that's capable of running OG Xbox games, so can't test it myself.

[astarivi]

Yes, I have successfully produced and played several images. As for the --trim argument, while the resulting GOD files work, the amount of saved space can be inconsistent, as noted in issue #2.

For example, I converted the following Redump images to GOD using different methods and compared the resulting sizes:

Morrowind GOTY

• XDVDFS rebuilt image, then standard conversion: 1,020,399,616 bytes
• --trim argument conversion: 3,530,967,809 bytes
• Standard conversion: 7,455,961,088 bytes

Thousand Land

• XDVDFS rebuilt image, then standard conversion: 1,160,413,184 bytes
• --trim argument conversion: 3,530,969,088 bytes
• Standard conversion: 7,455,961,088 bytes

A full rebuild could be achieved using xdvdfs-core, but that’s beyond the scope of this PR.

For now, I plan to run a few more tests on the resulting GOD images, and I’ll mark this PR as ready for review once I'm finished.

[iliazeus]

LGTM