Make HDF5 Optional

A collaborator is working on building SELF and its dependencies on the Grace Hopper platform (ARM) and has been experiencing issues with compiling HDF5 for use in SELF. To reduce the "dependency hell", we need to provide a default / failover file IO option that does not depend on HDF5.

Some caveats
* When HDF5 is not available, HOPr input needs to be disabled (and documented)
* We need to support loading in the failover / default files and provide a conversion utility to HDF5 in the pyself modules.

The default files need to include
* Lagrange interpolating polynomials
* Mesh information
* Geometry information (mesh positions and metric terms)
*

To resolve this issue

- [ ] Create documentation for the file failover file format
- [ ] Implement file IO for lagrange, mesh, geometry, and solution fields
- [ ] Implement file IO for metadata information
- [ ] Optionally build modules that depend on HDF5 (Cmake build system adjustment) - default file IO can always be available
- [ ] Add tests that exercise the default file IO