Create, Update, Destroy note on work items based on notes widget availability

What does this MR do and why?

This MR simply modifies the existing created, update, destroy mutations on notes to check for notes widget availability. And adds some related specs.

Because WorkItem model derives from Issue, we need to ensure that if a work item disables the notes widget it is still not possible to mutate the note(s) through endpoints still using legacy Issue model

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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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