Expose target triple information on `TranslatedLibrary`

[PathogenDavid]

Right now there isn't an easy way to figure out what platform the translated library is targeting. Generator authors can manually keep track of this, but ideally we'd just expose it directly from Clang.

I don't believe libclang is exposing this, and if it is it's probably only in string form. I'd rather not be in the business of parsing target triples so we should expose llvm::Triple in ClangSharp.Pathogen.

[PathogenDavid]

Once added this should be used to replace InlineExportHelper.__ItaniumExportMode with an automatic check. (Main issue: https://github.com/InfectedLibraries/Biohazrd/issues/209)