Update data conventions on names and units

[hboisgon]

Issue addressed

Fixes #45

Explanation

After a first discussion, we decided to have names of variables in hydromt be more explicit and a few new variables were added after review of existing plugins (wflow, sfincs, delwaq, delft3dfm)

To update conventions, need to:

• define them in the docs
• update the pre-defined catalogs (including artifact_data if possible)
• update the mentions in the code, especially the workflows and their docstrings

Checklist

• Updated tests or added new tests
• Branch is up to date with main
• Tests & pre-commit hooks pass
• Updated documentation if needed
• Updated changelog.rst if needed
• For predefined catalogs: update the catalog version in the file itself, the references in data/predefined_catalogs.yml, and the changelog in data/changelog.rst

Additional Notes (optional)

Add any additional notes or information that may be helpful.

[savente93]

@hboisgon do you think it will be feasible to include this in the alpha?

[hboisgon]

Not sure anymore. In this PR I would need to update the data catalogs but I don't know if it is a good idea to do it before PR #833 is merged?

[savente93]

Ah okay, I didn't realize the data catalogs needed to be updated. Then we can leave it.