GHOST data update

[lewisblake]

Is your feature request related to a problem? Please describe.

The GHOST data set used in CAMS61 has been updated to include a lot more data.
The paper is now in ESSD discussions https://essd.copernicus.org/preprints/essd-2023-397/ and the dataset is freely available here https://doi.org/10.5281/zenodo.10637449

It represents a massive effort of harmonization of measurements of atmospheric composition at the surface. In total, 7,275,148,646 measurements from 1970–2023, of 227 different components, from 38 reporting networks, are compiled, parsed, and standardised. Components processed include gaseous species, total and speciated particulate matter, and aerosol optical properties.

The main goal of GHOST is to provide a dataset that can serve as a basis for the reproducibility of model evaluation efforts across the community.

Describe the solution you would like to see
A clear and concise description of what you want to happen.

• Would you be able to work on this solution yourself?
  Probably not.
• How can the Pyaerocom development team assist you?
  People to download the data, people to write readers.

Additional context
Potentially a good first issue.