Add CosmicResampler StepPointMCs

@oksuzian has requested that we add the following to the EventNtuple for cosmic ray studies:

```
mu2e::StepPointMCs               CosmicResampler                     crvStage1        CosmicS2 
```

I think we already have a way to add StepPointMC collection branches so this may just require a change in fhicl