CT-1718: Add Note and Formatting event types

[peterallenwebb]

resolves #6481

Description

This PR replaces the EmptyLine event with a more general Formatting event. This new event isn't any semantically useful than EmptyLine, but let's us replace a broader set of events which are used only for formatting console output with a single event for that purpose which can be ignored for the purposes of structured logging.

This PR also adds a Note event, which is closer in spirit to the "FYI" event type mentioned in the original issue, and which dbt-server has asked us to include so that they can insert messages into the dbt log.

Checklist

• I have read the contributing guide and understand what's expected of me
• I have signed the CLA
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• I have opened an issue to add/update docs, or docs changes are not required/relevant for this PR
• I have run changie new to create a changelog entry

[github-actions]

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[gshank]

Looks good!