Update devcontainer Dockerfile (dotnet#52681)

* Update devcontainer Dockerfile

add missing tag

* Update Dockerfile

update to latest repo

* Update devcontainer.json

update csharp extension to new csharp dev kit
update tag list link

* remove VARIANT argument

* Update Dockerfile

revert image repo back

Author: WeihanLi

.devcontainer/Dockerfile

@@ -1,8 +1,6 @@
 # See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.177.0/containers/dotnet/.devcontainer/base.Dockerfile
 
-# [Choice] .NET version: 5.0, 3.1, 2.1
-ARG VARIANT="5.0"
-FROM mcr.microsoft.com/vscode/devcontainers/dotnet
+FROM mcr.microsoft.com/vscode/devcontainers/dotnet:latest
 
 # [Option] Install Node.js
 ARG INSTALL_NODE="true"

.devcontainer/devcontainer.json

@@ -5,20 +5,14 @@
   "build": {
     "dockerfile": "Dockerfile",
     "args": {
-      // The VARIANT here must align with a dotnet container image that
-      // is publicly available on https://mcr.microsoft.com/v2/vscode/devcontainers/dotnet/tags/list.
-      // We'll default to `latest` as the default. Generally, the .NET version that is baked
-      // into the image by default doesn't matter since we end up installing our own
-      // local version and using that by default in the container environment.
-      "VARIANT": "latest",
       // Options
       "INSTALL_NODE": "true",
       "NODE_VERSION": "lts/*"
     }
   },
   // Add the IDs of extensions you want installed when the container is created.
   "extensions": [
-    "ms-dotnettools.csharp",
+    "ms-dotnettools.csdevkit",
     "EditorConfig.EditorConfig",
     "k--kato.docomment",
     "dbaeumer.vscode-eslint"