Ensure that RefreshAccessToken uses correct HttpClient

[evolvedlight]

This fixes #324 by changing RefreshAccessToken to use the provided HttpClient

Checklist

General Contributing

• Have you read the Code of Conduct and signed the CLA?

Is This a Code Change?

• Non-code related change (markdown/git settings etc)
• SDK Code Change
• Example/Test Code Change

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[CLAassistant]

All committers have signed the CLA.

[greg-db]

Thanks for putting this together! I'll ask the team to review this.