Flexible support configuration

[MattWellie]

Fixes

• We have no way of flexing the importance of any individual category from full to support via configuration

Proposed Changes

• removes reference to "categorysupportX" in the documentation, that name prefix is no longer a usable mechanic
• adds a support_categories entry to the config template, this is pulled into each variant as an attribute, and contains the names of all the categories to use with second-tier importance
• reeeeeeallly simplifies the logical tests. Instead of treating full and support categories separately, and having a test for each combination, this is boiled down to a single method:

1. get all the categories that apply to this variant (Boolean) and this [sample + variant] (Sample) as a set of Strings
2. if support is not being used in this test, subtract all the category names in the support_categories list
3. return True if there's anything left in the list

ALSO

Adds a configurable minimum number of alt-supporting reads for a variant to reach the report

Checklist

• Related Issue created
• Tests covering new change
• Linting checks pass

[cassimons]

Looks great!