Mail methods refactor
Mail method should be refactored so that:
- We avoid duplicated code in mailAccount/mailGroup/sympaAliasPartage
- We avoid connecting to the mail server when it’s not needed
- Even lazily load quota info to speed-up account edition?
- Support correctly server change (partly done)
- Maybe improve server change with the same method?
- Hide non-supported fields (or check that this is the case already)