Reduce copying of records in the BP

[Utumno]

We make way too many copies (deepcopy is really expensive!) - right now we copy every record that a patcher is interested in once for every mod in the load order, but we really only need a copy of the since that's the version of the record we'll let the patchers modify

• [ ] Drop the getTypeCopy calls from the patchers
• [ ] Add a new phase after scanLoadMods in which we make one(!) copy of every record in the BP
• ~~save: getSize copies the entire grup in a BytesIO - we effectively dump the file twice. Replace this with dump returning the size and then seek back to write the size (O(top-groups) seeks can't be slower than this) - py3+~~ we would need too many seeks