[#6628] port [#4449] CloudAdapter always builds Connector with MicrosoftAppCredentials (never CertificateAppCredentials) -- certificate auth flow broken

[sw-joelmut]

Fixes #6628

Description

This PR add the CertificateServiceClientCredentialsFactory class to allow bot authentication with a certificate.

Note: to provide a certificate, add the CertificateServiceClientCredentialsFactory class to the bot's service collection in the Setup.cs file.

// Setup.cs file.
// Note: add `Configuration["MicrosoftAppTenantId"]` to the `tenantId` parameter when using `SingleTenant`.

services.AddSingleton<ServiceClientCredentialsFactory>((e) => new CertificateServiceClientCredentialsFactory(certificate, Configuration["MicrosoftAppId"], Configuration["MicrosoftAppTenantId"]));

Specific Changes

• Added CertificateServiceClientCredentialsFactory class to instantiate and use the CertificateAppCredentials.
• Added CertificateServiceClientCredentialsFactoryTests class with all the unit tests for the methods.

Testing

The following image shows the changes working as expected.

[coveralls]

Pull Request Test Coverage Report for Build 351865

• 0 of 0 changed or added relevant lines in 0 files are covered.
• 3 unchanged lines in 3 files lost coverage.
• Overall coverage increased (+0.03%) to 79.058%

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Files with Coverage Reduction	New Missed Lines	%
/libraries/AdaptiveExpressions/BuiltinFunctions/GetNextViableTime.cs	1	90.91%
/libraries/AdaptiveExpressions/BuiltinFunctions/GetPreviousViableTime.cs	1	90.91%
/libraries/integration/Microsoft.Bot.Builder.Integration.AspNet.Core/ServiceCollectionExtensions.cs	1	93.55%

Totals
Change from base Build 351371:	0.03%
Covered Lines:	25874
Relevant Lines:	32728

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💛 - Coveralls

[BruceHaley]

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