Move module and ORM cache outside of persistent storage

[tomudding]

Current behaviour

To prevent issues with configs not updating or ORM not picking up changes in models we should move their respective caches outside of data/ or limit the persistence of data/ to some of its subdirectories.

Desired behaviour

No response

Steps to reproduce

Website version

latest

What operating are you seeing the problem on?

No response

What browsers are you seeing the problem on?

No response

Other information

No response

[tomudding]

Move to a new folder cache in the root (so completely outside of data). That should make the persistance story a bit easier:

• cache: volatile
• data: persistent
• public: persistent (but should really change in the future).

[tomudding]

We can also remove the mail folder in data as we no longer use fs-based mail storage.