content_migrations pre_attachement methods params fix

methods in content_migrations.py were updated to support the pre_attachment[*] parameters. These can take any of the file upload options name, size, parent_folder, content_type, parent_folder_path, and on_duplcate. The method params were added to the method in a way that is consistent with the rest of the SDK. params describing each of these were added to the doc string and the pre_attachment[*] data was added to the payload. Default values were set to None. Also, in this commit, a new folder called static_methods was added. This folder will contain files that correspond to SDK modules with a "_replace_methods" added. These are where we will store methods that were manually updated. These methods will need to be reapplied after running the generate script. Eventually we can incorporate this into the generate script.