Config file error message for duplicate keys fixed and improved

[amart241]

🗣 Description

💭 Motivation and context

This will fix add an error message when 2 or more keys are added to a yaml config file. This will resolve #1218.

Closes #1218

🧪 Testing

I have ran this update with several config files to make sure it works as well as a unit test.

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[schrolla]

@amart241 Can you rework the PR title to better indicate what it actually fixes? Maybe something like "Improve config file invalid syntax error feedback"?

[schrolla]

@amart241 Also, please set the project fields for the PR per the pre-approval checklist.

[amart241]

Changed files according to feedback.

[amart241]

Done with new comments

[schrolla]

Latest updates address previous comments. Final test has the error coming thru looking clean and readable by the user. Well done.

[schrolla]

@nanda-katikaneni This PR is ready for merge.