Mail should redirect to AccountManager only for gmail accounts

• /e/ version: v1.0-beta2
• Device model(s): all
• Device rooted: yes/no

Summary

We cannot setup some accounts like hotmail because ~Mail redirect the user to ~"Account Manager". Only gmail account should be redirected to ~"Account Manager".

The problem

Steps to reproduce

Trying to add a hotmail.fr account from ~Mail

What is the current behavior?

You will be redirect to ~"Account Manager" and there is no way to add this kind of account.

What is the expected correct behavior?

Like K9 upstream, you should be able to setup manually this account form ~Mail app.

cc @rhunault