Custom timeout set via API shows as blank in UI

[ghost]

Is your feature request related to a problem? Please describe.
In the upcoming 2.0 release, we are introducing an authentication timeout option. However, the API allows setting a timeout that isn't one of the default options that is shown as a blank option in the UI selectbox.

Describe the solution you'd like
Show this as a custom option like Custom timeout: 18056Hrs and allow setting custom timeout via UI.

Describe alternatives you've considered
Prevent a custom value being set via API