VizSuite breaks with length-1 episodes, does not support arbitrary action spaces/distributions

## Problem

Some visualization types assume episode lengths > 1. VizSuite further assumes action spaces are Discrete(n).

## Steps to reproduce

Modify `projects/tutorials/running_inference_tutorial.py` with:
```
def machine_params(self, mode="train", **kwargs):
res = super().machine_params(mode, **kwargs)
if mode in ["test", "valid"]:
res.set_visualizer(self.get_viz(mode))

return res

@classmethod
def training_pipeline(cls, **kwargs):
pipeline = super().training_pipeline(**kwargs)
pipeline.save_interval = 1
return pipeline
```

Then run training with
`python main.py projects/tutorials/running_inference_tutorial.py -o debug_valid_viz -l debug`