port: Add Software Bill of Materials task for C# (#6047)

[github-actions[bot]]

The changes in Add Software Bill of Materials task for C# (#6047) may need to be ported to maintain parity with microsoft/botbuilder-dotnet.

Fixes #minor

Description

Need "software bill of materials" for our public facing products, per Presidential Executive Order.

Specific Changes

Task 'Generate Software Bill of Materials' added to signing build.

Please review and, if necessary, port the changes.