[WIP] User Story - Exploratory Statistics

[jerowe]

Before the PCA or PBS a scientist would complete several rounds of exploratory statistics and filtering.

1. Look at distributions of the data
2. Filter variants based on quality
3. Subset genotypes based on previous variant statistics
4. Filter samples (missingness)
5. Subset genotypes based on previous sample statistics

Reference the Breaking down the PCA PR

[jerowe]

1. General exploratory statistics

2. Variants Quality

3. Filter Genotypes based on Variant Quality

4. (and 5) Explore Sample Statistics

[jerowe]

@daletovar this is shared between the PCA and PBS user stories.