Add ExercisePreview component

[mateuszkornecki]

Is your feature request related to a problem? Please describe.
Part of the #165.
Describe the solution you'd like
we need this one to somehow show our therapist how the exercise prepared for the patient will look like, so the therapist will know. if the applied settings are correct.
Describe alternatives you've considered
We can basically just render the tiny Pointer in the small box and use the applied configuration to decide how the Pointer should behave.
Additional context