Cleanup the EyeTracking Demo code and other HL2 artifacts

[wiwei]

There's significant technical debt in the eye tracking demo code which we should clean up.

This has been filed to make sure we don't lose some of the interesting TODOs or comments in the following PR:

https://github.com/Microsoft/MixedRealityToolkit-Unity/pull/3755

[wiwei]

InputPointVisualizer.cs had a large TODO:

/// ------------ /// TODO /// ------------ /// - Load log files /// - Replace GameObjects with particle systems for higher perf on HoloLens /// - Question: How to visualize data from multiple ppl? Color lookup table? Limit number of scanpaths visible at a time? /// - Question: How can users load files from HoloLens? Built-in file explore? Load by session? /// - Allow for tweaking parameters while viewing the scene, such as "transparency" etc. /// ------------

Also VisModes needs summaries.

[wiwei]

LogStructure_EyeGaze had a lot of TODO code (around raw eye gaze tracking) removed.

[wiwei]

OnSelect_VisualizerInputController.cs needs tooltips for its serialized fields

[wiwei]

ParticleHeatmap_ParticleData.cs needs a summary

[wiwei]

UserInput_Playback.cs needs significant cleanup (see the original PR)

[wiwei]

WindowsMixedRealityEyeGazeDataProvider.cs needs work around its confidenceOfSaccadeThreshold

[wiwei]

Need to also followup on Interactable.cs's

        if (!CanInteract() || true)
        {
            return;
        }

        if (StateManager != null)
        {
            if (eventData == null && (HasFocus || IsGlobal)) // handle brute force
            {
                StateManager.SetStateValue(InteractableStates.InteractableStateEnum.Visited, 1);
                IncreaseDimensionIndex();
                OnClick.Invoke();
            }
            else if (eventData != null && ShouldListen(eventData.MixedRealityInputAction))
            {
                StateManager.SetStateValue(InteractableStates.InteractableStateEnum.Visited, 1);
                IncreaseDimensionIndex();
                OnClick.Invoke();
                eventData.Use();
            }
        }
        */

[Yoyozilla]

I think this is done?

[keveleigh]

Some is in progress with #4032

[Yoyozilla]

4032 is merged. closing issue.