Language-specific VSCode `extensions.json`

[weikanglim]

We currently don't have an extensions.json defined specific for each language (we only recommend azd extension). We should add this to clue the user in on the language specific VSCode extension for the debugger in our shipped VSCode tasks to work.

[savannahostrowski]

We should consider:

1. What do contributors need to have a good developer experience
2. What do end users need for templates (probably want one per language)

[bwateratmsft]

Here's the ones I'd recommend--

All:

• AZD (of course) (ms-azuretools.azure-dev)
• Azure Resources (ms-azuretools.vscode-azureresourcegroups)
• YAML (redhat.vscode-yaml)

C#:

• C# (ms-dotnettools.csharp)

Java:

• Extension Pack for Java (vscjava.vscode-java-pack)

JavaScript / TypeScript:

• ESLint (dbaeumer.vscode-eslint)

Python:

• Python (ms-python.python)
• Pylance (ms-python.vscode-pylance)

This list excludes built-in extensions that are needed (like the JS debugger and NPM support), and dependencies that will be auto installed (like Azure Account or Bicep)

[jongio]

We can use the list that is in devcontainer.JSON

[rajeshkamal5050]

@savannahostrowski @bwateratmsft

Moving this to backlog. Don't think we are doing anything w.r.t to this in Gallium.