update devcontainer for azure functions

.devcontainer/Dockerfile

@@ -0,0 +1,18 @@
+# Find the Dockerfile for mcr.microsoft.com/azure-functions/dotnet:3.0-dotnet3-core-tools at this URL
+# https://github.com/Azure/azure-functions-docker/blob/master/host/3.0/buster/amd64/dotnet/dotnet-core-tools.Dockerfile
+FROM mcr.microsoft.com/azure-functions/dotnet:3.0-dotnet3-core-tools
+
+# Uncomment following lines If you want to enable Development Container Script
+# For more details https://github.com/microsoft/vscode-dev-containers/tree/master/script-library
+
+# Avoid warnings by switching to noninteractive
+ENV DEBIAN_FRONTEND=noninteractive
+
+ARG INSTALL_ZSH=true
+ARG USERNAME=vscode
+ARG USER_UID=1000
+ARG USER_GID=$USER_UID
+
+RUN apt-get update && curl -ssL https://raw.githubusercontent.com/microsoft/vscode-dev-containers/master/script-library/common-debian.sh -o /tmp/common-script.sh \
+    && /bin/bash /tmp/common-script.sh "$INSTALL_ZSH" "$USERNAME" "$USER_UID" "$USER_GID" \
+    && rm /tmp/common-script.sh 

.devcontainer/devcontainer.json

@@ -1,11 +1,23 @@
 {
-    "extensions": [
-        "ms-azuretools.vscode-azurefunctions",
-        "ms-dotnettools.csharp",
-        "github.github-vscode-theme"
-    ],
-
-    "settings": {
-        "workbench.colorTheme": "GitHub Dark"
-    }
-}
+	"name": "Azure Functions & C# (.NET Core 3.1)",
+	"dockerFile": "Dockerfile",
+	"forwardPorts": [ 7071 ],
+
+	// Set *default* container specific settings.json values on container create.
+	"settings": {
+		"terminal.integrated.shell.linux": "/bin/bash"
+	},
+
+	// Add the IDs of extensions you want installed when the container is created.
+	"extensions": [
+		"ms-azuretools.vscode-azurefunctions",
+		"ms-dotnettools.csharp",
+		"github.github-vscode-theme"
+	],
+
+	// Use 'postCreateCommand' to run commands after the container is created.
+	// "postCreateCommand": "dotnet restore",
+
+	// Comment out connect as root instead. More info: https://aka.ms/vscode-remote/containers/non-root.
+	"remoteUser": "vscode"
+}

.vscode/settings.json

@@ -1,5 +1,5 @@
 {
-    "azureFunctions.deploySubpath": "src/bin/Release/netcoreapp2.1/publish",
+    "azureFunctions.deploySubpath": "src/bin/Release/netcoreapp3.1/publish",
     "azureFunctions.projectLanguage": "C#",
     "azureFunctions.projectRuntime": "~3",
     "debug.internalConsoleOptions": "neverOpen",