Option to change Email subjects

Is your feature request related to a problem? Please describe.

Please add an Parameter to change Email Subjects both for invitation and updates

Reason:

there is an long standing bug (or did the call it "ist a feature not a bug") in Microsoft Exchange, which takes the Email Subject as the Event Title and even changes it on an invitation update to the Email Subject, instead of using the correct title in the .ics Attachement.

As we both use Nextcloud and some users also Exchange, this leds to the following curious effects:

A event sent from Nextcloud to Exchange gets an title like "Invitation: Title of Event" instead just "Title of Event"

And after updating the event on Nextcloud the title in Exchange changes to "Invitation updates: Title of Event"

So it would be nice to change the subjects line to just keep the title (as Exchange does it)

Describe the solution you'd like

No response

Describe alternatives you've considered

No response

Additional context

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Start by locating the code path that composes email subjects for invitations and event updates. Clarify how subject parameters should be configured and verify that both flows can retain the event title without unwanted prefixes, including the Exchange interoperability case described in the issue.