Move ComponentLink back to blueocean-core-js so external plugins can …

[stuartrowe]

…extend it

Description

See JENKINS-XXXXX.

Submitter checklist

• [ ] Link to JIRA ticket in description, if appropriate.
• [ ] Change is code complete and matches issue description
• [ ] Appropriate unit or acceptance tests or explanation to why this change has no tests
• [ ] Reviewer's manual test instructions provided in PR description. See Reviewer's first task below.

Reviewer checklist

• [ ] Run the changes and verified the change matches the issue description
• [ ] Reviewed the code
• [ ] Verified that the appropriate tests have been written or valid explanation given