Enables the use of offline reason for all "offline" statuses (those that are not ONLINE/REPORTED) and makes it optional

[mitchell852]

This change treats any status that is not ONLINE/REPORTED as "offline" and therefore the offline reason is available for use.

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Which Traffic Control components are affected by this PR?

• Traffic Ops
• Traffic Portal

What is the best way to verify this PR?

If this is a bugfix, which Traffic Control versions contained the bug?

PR submission checklist

• [ ] This PR has tests
• [ ] This PR has documentation
• [x] This PR has a CHANGELOG.md entry
• [ ] This PR DOES NOT FIX A SERIOUS SECURITY VULNERABILITY (see the Apache Software Foundation's security guidelines for details)