Remove save_version type #873
Description
At some point, a "save_version" type was added to df-structures which maps the internal save version numbers to public release version names. However, this type was last updated in version 0.47.05, so it's currently completely useless.
In theory, we could add the new save version numbers for 50.01 through 53.10, but I don't believe they are actually useful - some versions of DF updated without incrementing the save version (which would make them indistinguishable), and some versions incremented the save version multiple times (which would make the enum less useful in Ghidra).
I think we should remove this type from df-structures and instead document it on the Dwarf Fortress Wiki somewhere.