Custom Delay for All APIs & for Each API

[FabrizioBrancati]

Is your feature request related to a problem? Please describe.
It would be useful to have a custom delay for all the APIs and even for each API. With that, we will be able to better simulate a real backend.

Describe the solution you'd like
Add a simple TextField in the App Settings to allow a custom delay for all APIs.
This field should allow an Int value or a Double value. We can even try with a simple Slide that allows the user to add a delay from 0.1 to 90 seconds, but it will be hard to use and select the right value.

The same TextField/Slider should be added in the Editor section while adding or editing an API, to allow a custom delay for each API. This value will override the app one, only for that API.

Describe alternatives you've considered
None.

Additional context
None.