Add possibility to disable calendar reminders

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

Since a while the Nextcloud Android app shows reminders for upcoming calendar events. Unfortunately these reminders are also shown by the default calendar app on my smartphone, so that I'm now receiving reminders for upcoming events twice each time. I've searched the app settings but haven't found a way to disable this function.

**Describe the solution you'd like**

Therefore I would like to request to add an option to the app which allows to disable calendar reminders.

**Describe alternatives you've considered**

Disabling all notifications of the Nextcloud app isn't an option because you wouldn't receive any file upload notifications anymore.

**Additional context**
Nextcloud server: 31.0.6
Calendar app: 5.3.4

Phone: Samsung Galaxy S25
Nextcloud app: 3.32.0 RC1