change displayName with IEventDispatcher

[Superjamp]

No description provided.

[juliushaertl]

@Superjamp Thanks for your pull request. Could you add some additional details on if that was due to any specific issues you encountered? I've just been debugging an issue that potential display name changes were not propagated to the user account data, to be more specific, the display name shown in the user profile. Is that similar to what you encountered?

Steps I had for running into this:

• Have a SAML user who already was logged in
• The display name mapping value changes
• The user logged in again through SAML
  -> Now the display name was only changed in the saml database table, not on the oc_accounts entry

[juliushaertl]

Tested and fixes the issue I was hunting 👍

[blizzz]

CI phpunit fails, seems like an issue with the tests themselves though.

[Superjamp]

@juliushaertl 👍
I came across this some time ago and now I have not found a good explanation of the way you did it for a pull request.
But it is the same Issue/steps to reproduce I had last year.

[juliushaertl]

Looks like it is actually a regression from nextcloud/server#27474

Test failures seem expected due to the fact that the event dispatcher is not injected and therefore not mocked in the unit test cases. Will see if I can push a fix for that.

[juliushaertl]

I've pushed your commit with an additional one for the tests to #582

[blizzz]

superseded by #582