Remove notifications upon user deletion

[nickvergessen]

Ref #1551

Not sure if this is correct, or if it should be done by the app. When it's done by the app, each of the apps would need to listen to the hook. What's different from comments to notifications, is that comments stores the data inside "core/server" instead of an app.

@LukasReschke @MorrisJobke thoughts?

[mention-bot]

@nickvergessen, thanks for your PR! By analyzing the annotation information on this pull request, we identified @icewind1991, @blizzz and @LukasReschke to be potential reviewers

[MorrisJobke]

Tested and works 👍

[blizzz]

Any form of tests possible?

[nickvergessen]

Create a "local" federated share and then delete the recipient.
Afterwards check the notifications table

[MorrisJobke]

Any form of tests possible?

• create a remote share with this user
• log in as user and check if there is the bell with the red dot in the top right (don't click it)
• delete user
• create user with same name
• login as new user
• no share notifiaction should be there

[blizzz]

I mean, automated tests. We would not notice if it breaks.

[nickvergessen]

Hmm let me try to hack into the IUser test when deleting a user, should be possible.

[nickvergessen]

Added tests for deleting preferences, comments and notifications.
Also made sure the "post" hooks are only triggered, when the deletion was successful...

[MorrisJobke]

@nickvergessen signed-off comment is missing ;)

[MorrisJobke]

@nickvergessen signed-off comment is missing ;)

Rebase fixes the detection script.

[nickvergessen]

Rebased

[blizzz]

LGTM

[MorrisJobke]

👍