Cache test data on Azure Pipelines

[weiji14]

Description of proposed changes

Windows builds on Azure Pipelines can't seem to fetch GMT data from http://oceania.generic-mapping-tools.org/, as mentioned in #434 (comment). This Pull Request mimics the upstream GMT one at GenericMappingTools/gmt#3056.

Files we are caching includes:

• @earth_relief_10m
• @earth_relief_60m
• @ridge.txt
• @Table_5_11.txt
• @tut_quakes.ngdc
• @tut_ship.xyz.

Fixes #

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 adding new functionality, add an example to docstrings or tutorials.

[weiji14]

Thanks for spotting the $HOMEPATH fix! We're now down to the 3 errors below. Will resolve them in separate Pull Requests to make things easier to review. Merging this in now.

================================== FAILURES ===================================
 __________________ [doctest] pygmt.clib.conversion._as_array __________________
 221 
 222     Examples
 223     --------
 224 
 225     >>> import pandas as pd
 226     >>> x_series = pd.Series(data=[1, 2, 3, 4])
 227     >>> x_array = _as_array(x_series)
 228     >>> type(x_array)
 229     <class 'numpy.ndarray'>
 230     >>> x_array
 Expected:
     array([1, 2, 3, 4])
 Got:
     array([1, 2, 3, 4], dtype=int64)
 
 C:\Miniconda\envs\testing\Lib\site-packages\pygmt\clib\conversion.py:230: DocTestFailure
 ___________ [doctest] pygmt.clib.conversion.kwargs_to_ctypes_array ____________
 263     Returns
 264     -------
 265     ctypes_value : ctypes array or None
 266 
 267     Examples
 268     --------
 269 
 270     >>> import ctypes as ct
 271     >>> value = kwargs_to_ctypes_array('bla', {'bla': [10, 10]}, ct.c_int*2)
 272     >>> type(value)
 Expected:
     <class 'pygmt.clib.conversion.c_int_Array_2'>
 Got:
     <class 'pygmt.clib.conversion.c_long_Array_2'>
 
 C:\Miniconda\envs\testing\Lib\site-packages\pygmt\clib\conversion.py:272: DocTestFailure
 ______________________________ test_pygmtscraper ______________________________
 
     @pytest.mark.skipif(sphinx_gallery is None, reason="requires sphinx-gallery")
     def test_pygmtscraper():
         "Make sure the scraper finds the figures and removes them from the pool."
     
         showed = [fig for fig in SHOWED_FIGURES]
         for _ in range(len(SHOWED_FIGURES)):
             SHOWED_FIGURES.pop()
         try:
             fig = Figure()
             fig.coast(region="BR", projection="M6i", land="gray", frame=True)
             fig.show()
             assert len(SHOWED_FIGURES) == 1
             assert SHOWED_FIGURES[0] is fig
             scraper = PyGMTScraper()
             with TemporaryDirectory() as tmpdir:
                 conf = {"src_dir": "meh"}
                 fname = os.path.join(tmpdir, "meh.png")
                 block_vars = {"image_path_iterator": (i for i in [fname])}
                 assert not os.path.exists(fname)
 >               scraper(None, block_vars, conf)
 
 C:\Miniconda\envs\testing\Lib\site-packages\pygmt\tests\test_sphinx_gallery.py:36: 
 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
 C:\Miniconda\envs\testing\Lib\site-packages\pygmt\sphinx_gallery.py:35: in __call__
     return figure_rst(image_names, gallery_conf["src_dir"])
 C:\Miniconda\envs\testing\Lib\site-packages\sphinx_gallery\scrapers.py:264: in figure_rst
     figure_paths = [os.path.relpath(figure_path, sources_dir)
 C:\Miniconda\envs\testing\Lib\site-packages\sphinx_gallery\scrapers.py:264: in <listcomp>
     figure_paths = [os.path.relpath(figure_path, sources_dir)
 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
 
 path = 'C:\\Users\\VSSADM~1\\AppData\\Local\\Temp\\tmpl_p8uqy7\\meh.png'
 start = 'meh'
 
     def relpath(path, start=None):
         """Return a relative version of a path"""
         path = os.fspath(path)
         if isinstance(path, bytes):
             sep = b'\\'
             curdir = b'.'
             pardir = b'..'
         else:
             sep = '\\'
             curdir = '.'
             pardir = '..'
     
         if start is None:
             start = curdir
     
         if not path:
             raise ValueError("no path specified")
     
         start = os.fspath(start)
         try:
             start_abs = abspath(normpath(start))
             path_abs = abspath(normpath(path))
             start_drive, start_rest = splitdrive(start_abs)
             path_drive, path_rest = splitdrive(path_abs)
             if normcase(start_drive) != normcase(path_drive):
 >               raise ValueError("path is on mount %r, start on mount %r" % (
                     path_drive, start_drive))
 E                   ValueError: path is on mount 'C:', start on mount 'D:'
 
 C:\Miniconda\envs\testing\lib\ntpath.py:703: ValueError
 ---------------------------- Captured stderr call -----------------------------
 psconvert [ERROR]: Error opening HKLM key
 psconvert [ERROR]: Error opening HKLM key
 ============================== warnings summary ===============================
 C:\Miniconda\envs\testing\lib\site-packages\win32\lib\pywintypes.py:2
   C:\Miniconda\envs\testing\lib\site-packages\win32\lib\pywintypes.py:2: DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
     import imp, sys, os
 
 -- Docs: https://docs.pytest.org/en/latest/warnings.html
 
 ----------- coverage: platform win32, python 3.8.2-final-0 -----------