Add support for Secure Service Account API.

[tylerwarner33]

About

Add support for the Secure Service Account API recently released for 'General Availability' (GA).

References

• Secure Service Account API - Documentation
• Secure Service Account API - Blog Post
• Secure Service Account API - Sample App

Changes

• New API / Nuget Package added to support the Secure Service Account API.
• Added as a subset of the Authentication API based on endpoint routes (adjust as needed).

Testing

• A tests.runsettings file can be created with this format to populate the environment variables in the test suite.

<?xml version="1.0" encoding="utf-8"?>
<RunSettings>
	<RunConfiguration>
		<EnvironmentVariables>
			<clientId></clientId>
			<clientSecret></clientSecret>
			<twoLeggedToken></twoLeggedToken>
			<serviceAccountName></serviceAccountName>
			<serviceAccountFirstName></serviceAccountFirstName>
			<serviceAccountLastName></serviceAccountLastName>
			<serviceAccountId></serviceAccountId>
			<pathToPrivateKeyFile></pathToPrivateKeyFile>
			<keyId></keyId>
		</EnvironmentVariables>
	</RunConfiguration>
</RunSettings>