XD-2306: Ability to upload modules

A new type of ModuleRegistry that supports saving uploaded modules.
The current behavior is for that registry to not allow deletion of modules which are in exploded form, which is a nice way of not allowing OOTB modules at the moment.

An alternative will be to use a different root folder for uploaded modules
Note that this method also attempts to create it (if needed), which is less clear in your proposal (IMHO)