Move label to id

[tetron]

• In the tests YAML, replace id with the contents of label and remove label
• Deprecate label
  • If both label and id are present, then label will be used for messages.
• Explain all this in https://github.com/common-workflow-language/cwltest/blob/main/cwltest/cwltest-schema.yml
• Make sure the test id is printed on each line along with the N/M
• Adjust documentation of command line option -s to indicate it takes a list of ids
• Add new command line option that takes a list of test ids to exclude: new command line option that takes a list of test ids to exclude #111

[tom-tan]

After merging #137, we can check Make sure the test id is printed on each line along with the N/M in the list.