Update acoustic material class

[williameaton]

Description

Updates the acoustic_material class with a working constructor and associated print and get_properties function.

Issue Number

68

Checklist

Please make sure to check developer documentation on specfem docs.

• [x] I ran the code through pre-commit to check style
• [ ] My code passes all the integration tests
• [ ] I have added sufficient unittests to test my changes - WILL BE ADDED SOON
• [x] I have added/updated documentation for the changes I am proposing
• [ ] I have updated CMakeLists to ensure my code builds
• [x] My code builds across all platforms

[Rohit-Kakodkar]

okay to test

[Rohit-Kakodkar]

retest this please

[Rohit-Kakodkar]

retest this please

[williameaton]

Added two commits to fix formatting and remove relic functions no longer requierd.