Resource user mention notifications

[fschade]

Description

opencloud-eu/web#2601 by @JammingBen introduces the ability to mention users in collabora,
even if the ability for user completion on its own is already great, letting users know that they got mentioned is key requirement to make it feel complete.

The two channels for such notifications are: mail and sse.

SSE pops up in the web ui during usage, mail will pop up in the users inbox if the web-app is not opened.

Open questions

skip or fail notification

in some cases, mentioning users in private documents could be crucial, what should we do if the user has no access to the document?

• a: error and do not notify any user at all?
• b: ignore the user, dont fail and notify all the other users with access?

Related Issue

• Completes feat: implement user mentions in Collabora docs web#2601

Motivation and Context

as described in the description, letting users know is a key requirement, its important to note, the notification is only send if the user can access the resource he got mentioned in.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Technical debt
• Tests only (no source changes)

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation added

[codacy-production]

Not up to standards ⛔

_{NEW Get contextual insights on your PRs based on Codacy's metrics, along with PR and Jira context, without leaving GitHub. Enable AI reviewer
TIP This summary will be updated as you push new changes.}