feat(mail): unsubscribe newsletter

Related to #528

What does this MR do and why?

• create a route that accepts a token
• disable the sendNotification without being connected
• call the permissions API
• sends the token in the mail

Screenshots or screen recordings

These are strongly recommended to assist reviewers and reduce the time to merge your change.

How to set up and validate locally (or on alpha)

• yarn build-dev
• enable the newsletter in options
• run yarn run cozy-konnector-dev -m manifest.webapp ./build/services/monthlyReportNotification/ecolyo.js
• you should receive a mail inside mailhog
• copy the link behind "Se désinscrre"
• go in a private browser to make sure you are not connected to your cozy
• open the link
• check your profile in chouchDB
• test that you can resubscribe with the first button

You can also test this on alpha

MR acceptance checklist

Also review updated documentation here self-data-technical-doc!56 (merged)

Quality -

• For the code that this change impacts, I believe that the automated tests validate functionality that is highly important to users. If the existing automated tests do not cover this functionality, I have added the necessary additional tests or I have added an issue to describe the automation testing gap and linked it to this MR.
• I have made sure that the sonar quality coverage is up to standards.
• I have considered the impact of this change on the front-end, back-end, and database portions of the system where appropriate and applied.
• I have tested this MR in all supported browsers or determined that this testing is not needed.
• I have confirmed that this change is backwards compatible across updates (migrate up needs a migrate down), or I have decided that this does not apply.

Performance, reliability and availability

• I am confident that this MR does not harm performance, or I have asked a reviewer to help assess the performance impact.
• I have considered the scalability risk based on future predicted growth.

Documentation

• The MR is named after the desired squash commit to feed the changelog linked to the current milestone.
• I have added/updated documentation (also updated if the changes feature a deprecation) or I have decided that documentation changes are not needed for this MR.

Security

• I have confirmed that if this MR does not contains any sensitive informations hidden in the changes.

Deployment

• When featured on a self-data project release, I have made sure my app version in the manifest and package.json is incremented and any relative changes to the permissions are clearly written and transmitted to Cozy.