format checking should be part of --validate

[mr-c]

In the example below, cwltool --validate should fail, as step first's that output has a static format that does not match step second's other input.

If steps.first.run.outputs.that.format was changed from iana:text/plain to $(inputs.this.format) then --validate should also fail as neither iana:text/plain nor iana:text/rtf match the required format iana:text/xml

• format checking of static formats
• format checking of pass through CWL expression formats

#!/usr/bin/env cwl-runner
cwlVersion: v1.0
class: Workflow

inputs: []

steps:
  first:
    run:
      class: CommandLineTool
      inputs:
        this:
         type: File
         format: [iana:text/plain, iana:text/rtf]
      baseCommand: whoami
      stdout: stdout.txt
      outputs:
        that:
          type: File
          format: iana:text/plain
          outputBinding:
            glob: stdout.txt
    in:
      this:
        default:
          class: File
          contents: Foo
          format: iana:text/plain
        
    out: [ that ]
  second:
    run:
      class: CommandLineTool
      inputs:
        other:
          type: File
          format: iana:text/xml
      baseCommand: echo
      arguments: [ $(inputs.other.format) ]
      outputs:
        result: stdout
    in:
      other: first/that
    out: [ result ]

outputs:
  result:
    type: File
    outputSource: second/result

$namespaces: { iana: https://www.iana.org/assignments/media-types/ }