[WIP] Add compressible EOS option to visco plastic material model

[naliboff]

An initial step towards adding the option to use the multicomponent_compressible EOS in the visco_plastic material model. In theory no functionality has changed with the initial commit and the goal is to see if all the tests pass.

@gassmoeller - two questions:

1. Following our initial conversation, does this structure look reasonable, or is there a more streamlined way to switch between the two EOS modules?
2. multicomponent_compressible currently does not support having more than one phase. Should I add this functionality to multicomponent_compressible first before proceeding with PR, or introduce logic internally within visco_plastic to handle this discrepancy?

For all pull requests:

• [X] I have followed the instructions for indenting my code.
• [ ] I have tested my new feature locally to ensure it is correct.
• [ ] I have created a testcase for the new feature/benchmark in the tests/ directory.
• [ ] I have added a changelog entry in the doc/modules/changes directory that will inform other users of my change.