Create an IO base class for exodus/nemesis IO

## Description
Some APIs are shared (duplicated) between the two IO classes and not having a base class currently forces to use lambda functions or if-statements to call the same APIs on an exodus or nemesis IO in MOOSE for loading those types of solution files

## Design
A base class for exodusII_io and nemesis_io
We need to find a name for it!

## Impact
Simpler downstream code
