--validate on a $graph CWL document should validate all objects without prompting

[mr-c]

Expected Behavior

cwltool --validate https://github.com/common-workflow-language/cwl-v1.2/raw/main/tests/conflict-wf.cwl validates all objects inthe file.

Actual Behavior

Tell us what happens instead

INFO /usr/bin/cwltool 3.0.20200807132242
ERROR Tool definition failed initialization:
Tool file contains graph of multiple objects, must specify one of #echo, #cat, #collision