Lesson 7 - add function filter

[yortch]

Create a function invocation filter that logs the functions that are being invoked:
Acceptance criteria:

• lesson and solution files are created
• lesson mkdocs files are added
• Tracing is enabled in deployable app
  https://github.com/microsoft/semantic-kernel/blob/main/dotnet/samples/Concepts/Filtering/AutoFunctionInvocationFiltering.cs
  https://github.com/Tyler-R-Kendrick/learn-sk/blob/main/dotnet/DemoApp/Core.Utilities/Filters/FunctionInvocationLoggingFilter.cs