fix: Add Audience for Certificate auth to work with Skills

[sw-joelmut]

#minor

Description

This PR adds Audience to CertificateAppCredentials, so it is passed correctly when calling a Skill bot. Additionally, these changes take into consideration the PR #6694, so the improvement isn't lost in the process.

Specific Changes

• Added missing oAuthScope parameter to libraries/Microsoft.Bot.Connector/Authentication/CertificateAppCredentials.cs.
• Improved libraries/Microsoft.Bot.Connector/Authentication/CertificateServiceClientCredentialsFactory.cs by reverting the changes made in the PR Support SN+I authentication with AAD #6694, but maintaining the improvement.
  • It creates a new instance of CertificateAppCredentials per Audience, instead of having just one with the default api.botframework.
• Added unit test to confirm it doesn't create new instances when the same Audience is provided.

Testing

The following images show the new unit test passing and the Root + Skill bots working as expected.

[coveralls]

Pull Request Test Coverage Report for Build 389711

Details

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 22 unchanged lines in 4 files lost coverage.
• Overall coverage decreased (-0.004%) to 78.171%

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Files with Coverage Reduction	New Missed Lines	%
/libraries/AdaptiveExpressions/BuiltinFunctions/GetPreviousViableTime.cs	1	90.91%
/libraries/AdaptiveExpressions/BuiltinFunctions/GetNextViableTime.cs	1	93.94%
/libraries/AdaptiveExpressions/LRUCache.cs	4	87.18%
/libraries/Microsoft.Bot.Connector/Authentication/CertificateAppCredentials.cs	16	17.07%

Totals
Change from base Build 389234:	-0.004%
Covered Lines:	26192
Relevant Lines:	33506

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💛 - Coveralls

[BruceHaley]

✔️ No Binary Compatibility issues for Microsoft.Bot.Connector.dll