Convert rotating disk and Wigley hull to cas.h5 format

[ansjsia]

Added cas.h5 versions of the rotating disk and Wigley hull mesh files to support using lightweight case loading in solver mode unit tests.

EDIT: Also converted all .msh files to .msh.h5 (for 3D meshes) or to .msh.gz (for 2D meshes). After merging this PR, the following PRs must also be merged to avoid breaking tests and examples:

• Unit test upgrade: https://github.com/ansys/pyfluent/pull/2296
• PyFluent examples: https://github.com/ansys/pyfluent/pull/2214
• PyFluent miscellaneous examples: https://github.com/ansys/pyfluent-examples/pull/99

[ansjsia]

I think it would be a good idea to not remove any files in this PR (even if you are fairly sure they aren't being used).

In a subsequent PR, when we do come back to remove the deprecated files, we should request review from the people who added these files, in case they are being used in ways that we did not anticipate.

@raph-luc Good point, I've restored all of the original .msh files.