Add tutorial section on passing xr.Dataset with 1-D data_vars as input

[weiji14]

Description of proposed changes

Show how an xarray.Dataset with 1-D data variables can be passed into the data parameter of PyGMT functions/methods.

Preview at https://pygmt-dev--3147.org.readthedocs.build/en/3147/get_started/04_table_inputs.html#xarray-dataset-with-1-d-data-variables

Addresses #3146, #1268

Reminders

• Run make format and make check to make sure the code follows the style guide.
• Add tests for new features or tests that would have caught the bug that you're fixing.
• Add new public functions/methods/classes to doc/api/index.rst.
• Write detailed docstrings for all functions/methods.
• If wrapping a new module, open a 'Wrap new GMT module' issue and submit reasonably-sized PRs.
• If adding new functionality, add an example to docstrings or tutorials.
• Use underscores (not hyphens) in names of Python files and directories.

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