i18n structure with alternative multiple_folders

[lorensansol]

In the general i18n support configuration, 3 options are offered for the structure:

Required and can be one of multiple_folders, multiple_files or single_file
multiple_folders - persists files in <folder>/<locale>/<slug>.<extension>
multiple_files - persists files in <folder>/<slug>.<locale>.<extension>
single_file - persists a single file in <folder>/<slug>.<extension>

An alternative multiple_folders (maybe single_folder) that persists files in <locale>/<folder>/<slug>.<extension> would be great.

[KaneFreeman]

I've made an issue for this. #973