Retraction amount setting for specified layer

[kacper-github]

Is your feature request related to a problem? Please describe.
In the current version of Prusaslicer, there is no way to perform a retraction test. (Print retraction tower)

Describe the solution you'd like
Add the possibility to set the retraction amount on the specified layer

Describe how it would work
In the retraction settings tab, I would like to have the possibility to add a pair Layer : Retraction value.
I would like to have an option to add multiple values. For example:
Layer: 1, Retraction: 0
Layer: 25, Retraction: 0.5mm
Layer: 50, Retraction: 1mm
Layer: 75, Retraction: 1.5mm
etc

Which means:
From layer 1 to 24 use retraction 0
From layer 25 to 49 use retraction 0.5mm
From layer 50 to layer 74 use retraction 1mm
From layer 75 to end of the print use retraction 1.5mm

Describe alternatives you've considered
Add custom G-CODE on the selected line. Make it similar to the extruder temperature change.

Additional context
To establish the best quality for my prints I need to test retraction in a couple of cases. I don't want to use for this task other slicers.

[rtyr]

Already requested in #3635, #2255. I am closing this one as a duplicate.