Adds API endpoint for getting a single draft note

What does this MR do and why?

Building on !110107 (merged), this MR adds an endpoint for returning a single Draft Note record.

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How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

MR acceptance checklist

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• I have evaluated the MR acceptance checklist for this MR.

Related to #321259 (closed)