Better handling of jq_filter and files

[dprunier]

This PR tries to restore the behavior which I believe was expected, based on JQ behavior.

Valid usage are:

• yq < file (not working with yq-2.10.1)
• yq filter < file
• yq filter file
• yq filter file1 file2 ...
• yq -f filter < file (not working with yq-2.10.1)
• yq -f filter file (not working with yq-2.10.1)
• yq -f filter file1 file2 ...

Invalid usage are:

• yq on a TTY
• yq filter on a TTY
• yq -f filter on a TTY

[kislyuk]

Thank you! You are absolutely right, these inconsistencies with the jq API need to be corrected.

Would you mind adding test assertions in test/test.py, just asserting that the commands succeed?

[dprunier]

Sorry, was on holidays. Yes, i will add these. Thanks.

[dprunier]

@kislyuk I just added a test case, which uncovered a regression (who says tests aren't useful :D)

[kislyuk]

Thanks! Really appreciate your help with this, and the thorough test case.