Provide Azure TypeSpec snippets

[timotheeguerin]

Clear and concise description of the problem

Azure part of microsoft/typespec#4559 (comment)

Options suggested:

• Make an azure snippet vscode extension
• Design a piece that allows tsp library to provide snippet
• Just add the snippet in the azure spec repo vscode config

Checklist

• Follow our Code of Conduct
• Check that this issue is about the Azure libraries for typespec. For feature request in the typespec language or core libraries file it in the TypeSpec repo
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.