Lesson 5 - List all plugins and functions

[yortch]

Using this code example create new lesson that lists all plugins and functions loaded in the kernel:

• Add lesson and solution files
• Add corresponding mkdocs file for Lesson 5
• Add new REST endpoint to output the plugins and functions loaded https://github.com/microsoft/semantic-kernel/blob/39934f5fa338141c8a64de96895a4e1f440638d7/dotnet/samples/Concepts/Plugins/DescribeAllPluginsAndFunctions.cs