RO-crate content appear in the nf-core lint warning if there is a TODO

[ningyuxin1999]

Changes:

1. The RO-crate-metadata.json is ignored in linting
2. Added a test script nf_core/pipelines/lint/rocrate_readme_sync.py for synchronizing the content of ROcrate metadata and the repo README.

The warning message mentioned here disappears when you create a new pipeline without deleting the TODO commands. But I still wonder where I should add the --fix flag so that the use can decide whether they want to synchronize the metadata with the readme file.

PR checklist

• This comment contains a description of changes (with reason)
• CHANGELOG.md is updated
• If you've fixed a bug or added code that should be tested, add tests!
• Documentation in docs is updated

[mirpedrol]

leaving a couple of comments, otherwise is looking good!