7 make noise dtype passable

[gfdb]

In this PR we do a few things.

1. We made noise_dtype passable directly from the wav2aug object. This will allow the user to specify how they would like to store the pointsource noises in memory e.g. fp32, fp16, etc...
2. We removed the option to load noise synchronously one file at a time using dataloaders cause it was super slow. If there are people who really don't want to consume ~1 GB (or less if using < fp32 for the pointsource noises, I'll add a dataloader option with support for multiple workers when those people complain.
3. Updated/added tests

closes #7