Add Defaultable for CommandInputRecordField

[tom-tan]

This is to solve common-workflow-language/common-workflow-language#641 by introducing a base type named Defaultable to the schema.

• one or more conformance tests
• testing with cwltool --enable-dev in a v1.1.0-dev1 document
  • add this test permanently
  • Okay, need to teach cwltool how to copy the default value over
  • update the spec
• test cwltool using v1.0 and a record field default (this should fail)
  • add this test permanently

[ghost]

@tom-tan we discussed this a bit and find the schema addition elegant. However there is a concern at the complexity implementation will entail. Could you please add (or point to) the cwltool implementation along with conformance tests, so we can discuss further. Thank you so much!

[tom-tan]

I made a re-done request to cwl-v1.3 (See common-workflow-language/cwl-v1.3#54).
Can I close this issue and continue it in common-workflow-language/cwl-v1.3#54?