Update the interface for calling fluid properties in coolant_values file

[lcarasik]

The current coolant values file calls the fluid properties in an inefficient way based on the old old matlab file. Needs to be more like fuel_props in the future. This would be something for a future project.

[lcarasik]

• Create dictionary for cladding properties
• Create interface for cladding properties in the tacocat.py
• Create test case for unit testing
• Create documentation outlining what it is and how to use it.

[sierratutwiler]

I'm a little confused by this issue, why are there cladding material action items on a fluid property issue? Is this resolved?