Modding: Allow replacing EXE text/data hardcoded in code

[myst6re]

Summary

Sometimes texts and textures are stored inside the EXE, instead in the data directory.
In this case it is harder for modders to mod the game.

This feature allows modders to override data from the EXE via the
Direct Mode feature.

Use the save_exe_data option to dump files to the direct/exe/ directory.
And then FFNx will look for those files directly instead of data from the EXE.

Supported data

FF8

• battle_scans.msd: Texts in battle scans. Note: this is not exactly the same
  format in the EXE, the msd format is used because it is a well documented format
  of FF8.

ACKs

• I have updated the Changelog.md file
• I did test my code on FF7
• I did test my code on FF8

[julianxhokaxhiu]

Thank you!