Implement a encode/decodeEXI command to the CLI

[jadams-tresys]

This command simply encodes an existing XML file to EXI using Exificient. It will do a schema aware encoding if a schema is provided. On the other side the decodeEXI command will decode an existing EXI file to a plain text XML file.

This is a useful feature as there isn't an easy existing way to perform these conversions using a schema aware encoding as it requires the use of the DaffodilXMLEntityResolver for anything more than a basic schema.

DAFFODIL-2750

[stevedlawrence]

+1 Looks pretty straightforward. Just some minor suggestions.

[tuxji]

I would like to request you make Steve's suggested changes and add additional test cases for error messages. I also would like to see #873 merged first since your changes are much smaller and the conflicts will be easier to fix & review in your pull request.

[tuxji]

I'm puzzled why we're seeing codecov check warnings that some lines are not covered by tests, when we do have a new test.

[tuxji]

I'm sure people will try to encode an EXI file and decode an XML file the wrong way around and they should see an appropriate error message.

I remember Mike commented in the JIRA issue that XML and EXI files look so different that we might not even need a --decode option. It may be more work to implement but it might be nice to have file type recognition rather than -d.

[stevedlawrence]

+1 looks good with minor suggestions and rebased to work with the latest master to get the exi factory from an EXIInfosetHandler.

[jadams-tresys]

All issues should be addressed, including errors that were being seen on Windows CI machines. @tuxji just need your approval as I removed the expectEOF function.

[tuxji]

+1