Added a test of GDAL opening a grid.asc file

[micheles]

The GDAL wheel provided by @vot4anto cannot open an ESRI .asc file: that breaks IPT in the Volcano example:

ERROR: openquakeplatform_ipt.test.examples_test.IptExamplesTest.ConfigurationFile_92_4_test
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/ubuntu/oq-platform-ipt/openquakeplatform_ipt/test/examples_test.py", line 476, in generated
    res = zip_diff(exp_filename, zipfile, True)
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/ubuntu/oq-platform-ipt/openquakeplatform_ipt/test/examples_test.py", line 218, in zip_diff
    z2 = zipfile.ZipFile(open(filename2, "rb"))
                         ^^^^^^^^^^^^^^^^^^^^^
FileNotFoundError: [Errno 2] No such file or directory: '/home/ubuntu/gem-oq-moon-download/Volcano.zip'

My guess is a missing AAIGrid driver. Here I add a test, engine side, which actually gives a proper error message and not a confusing one.