Adapt auto-checkout default values (EXPOSUREAPP-6243) (#2791)

* Prepare calculation of defaultAutoCheckoutLength

* Not allow defaultCheckInLength < 15min and > 23h45min

* Add more test cases

* Make some tests green

* Make ALL tests green

* Disable Confirm-CheckIn Button when automatic checkout is set to 00:00

* Suppress detekt issue

* Add test for enabling and disabling the confirm button in ConfirmCheckInViewModel.kt

* Add and adapt some comments

* Extract default auto checkout duration logic to extension function

* Add test and comments for roundToNearest15Minutes

* Rename AutoCheckoutHelper.kt -> DefaultAutoCheckoutLength.kt

Co-authored-by: harambasicluka <64483219+harambasicluka@users.noreply.github.com>