Allow to to specify in the filter element to match the full path

[cofinoa]

New path attribute on filters to allow matching the full path instead only the name. See:
https://stackoverflow.com/questions/48445792/filtering-thredds-datasetscan-by-both-directory-and-file-pattern

Example of directory structure:

/GGG/alpha/a
          /b
          /c
/GGG/beta/a
         /b
         /c

the following <datasetScan>

<datasetScan name="Test Filtering" ID="testFiltering"
               path="testFiltering" location="/GGG">
    <filter>
      <include wildcard="*" atomic="true" collection="true"/>
      <exclude wildcard="*alpha/a" path="true" collection="true"/>
    </filter>
  </datasetScan>

will show all the directories except the alpha/a directory

[cwardgar]

This is definitely a worthwhile addition, but I hesitate to merge it into master, because catalog handling is vastly different in 5.0.0. I think we should target 5.0.0 only.

We'll need to:

• Add "path" attribute parsing to ConfigCatalogBuilder.readDatasetScan().
• Add "path" attribute to InvCatalog.1.2.xsd.
• Add unit test(s) to TestDatasetScanFilter.
• Update documentation.

I'll try to get to it before the release of 5.0.0. I'll leave this PR open and un-merged until then. Thanks for getting this started, @cofinoa.

[cofinoa]

Agree.

I was looking at the TDS4.6 source code to understand the datasetScan and it was too obvious to me how to implement that feature (which has been a long standing complain "among TDS admins").

[cofinoa]

@cwardgar I have migrate the master changes to the version 5.0.0 branch
https://github.com/cofinoa/thredds/tree/support_path_filter_v5

but I don't know how to add the unit tests to TestDatasetScanFilter, basically because of my lack of how to work with them.

If you provide me some basic instrucitions or guidance I can learn for future PR.

[cwardgar]

I'm converting this to an issue (#1032), just to clear out our open pull requests a bit.