End date of all day events should be the last second of the day

[Fasse]

If you have an all day event e.g. 24.02.2023 than we will now store
start date = '2023-02-24 00:00:00'
end date = '2023-02-25 00:00:00'

This will cause problems if you filter such events because if you search for dates of 25.02.2023 than you will also find that date but you don't want that.

We should save all day events in this form:
start date = '2023-02-24 00:00:00'
end date = '2023-02-24 23:59:59'