Context
Currently, we have a sample_rate argument in our different tracker data deserializers, which allows us to generate a TrackingDataset output with lower fps (= frames per second) than the original tracking data.

Proposal
Add a fps_output argument in tracking data deserializers, which can be an arbitrary number. Based on this argument and the fps of the raw tracking data file, we will construct a TrackingDataset output with the desired fps output. We will use sampling (to reduce the fps of the original file) or interpolation (to increase the fps of the original file), or a combination of both if required.

Goal
By introducing a fps_output argument in tracking data deserializers, users can more easily append/concatenate tracking data of different data sources together. This way, they don't need to worry about generating consistent frames per second between different providers themselves.