Write and read mesh name attribute

[pshriwise]

Description

@shimwell aptly noted that user-specified names for Mesh objects are present in the Python API, but aren't written to XML or HDF5. This PR addresses that problem. There's also some refactoring so that common object information I/O occurs in the base classes on both the Python and C++ to reduce code duplication.

Some tests have been added to make sure this data is round-tripped properly to and from the XML and HDF5 formats.

Fixes #3213

Checklist

• I have performed a self-review of my own code
• I have run clang-format (version 15) on any C++ source files (if applicable)
• I have followed the style guidelines for Python source files (if applicable)
• I have made corresponding changes to the documentation (if applicable)
• I have added tests that prove my fix is effective or that my feature works (if applicable)

[shimwell]

This solved the issue nicely, many thanks Patrick. If there are no objections let us merge this in on Monday