Investigate adding additional TypeConverter metadata to Resx

Resx uses `TypeConverters` when available to convert data to/from `string` and `byte[]`. The specific type converter used isn't recorded, it's only the active one for `typeof(T)` that is considered. For unwrapping it would be good to know the specific type converter used and attempt to use the exact one if possible and give diagnostic information of some sort.

In order for this sort of change to have meaning, all copies of the Resx code need to be considered (MSBuild has their own, for example.)

cc @GrabYourPitchforks