Update sample with latest changes using Python as reference

[lilyjma]

Use the Python sample as a reference and do the following: https://github.com/Azure-Samples/mcp-sdk-functions-hosting-python

• Update the readme to match the Python sample's
• Update the content of the infra folder with what the Python sample has
• Remove the FUNCTIONS_CUSTOMHANDLER_PORT from the server code because that's not needed anymore. Update the host.json to include the original port used by the server instead.
• Remove the mcp-handler directory
• Anything I might've missed. Match the Python sample in terms of content, but keeping the language specific pieces of the current sample

Don't do anything else.