TF-2370 Cannot send email on Stalwart

[dab246]

Issue

#2370

Root cause

• Mailbox/changes on Stalwart does not work properly.
• Folder Outbox has already been created, so it cannot be created anymore.

Solution

• We will separate the Outbox handling function in SendEmailInteractor. Do not handle nested method in jmap request anymore.

Demo

• Server StartWalt:

https://github.com/linagora/tmail-flutter/assets/80730648/68f8f80d-72e8-4492-8d41-78c07b19a814

• Server Linagora:

https://github.com/linagora/tmail-flutter/assets/80730648/0cb25b0a-14bb-4334-9e74-30cc4d5568fe

[github-actions[bot]]

This PR has been deployed to https://linagora.github.io/tmail-flutter/2398.