First round of removing memoize

https://jira.gsc.wustl.edu/browse/AT-650

This first round of fixes removes all memoizes in VariantReporting that were used on an object instance subroutine without any additional parameters. They were converted into transient attributes.
A similar thing is possible with the available fields hash (dict?) here.

It's also interesting that when this calls into `SUPER` it will temporarily set the property with the result of that before overwriting it here.  (It should work in this case, but it's something of which to be aware.)