ide: update devcontainer configuration

.devcontainer/x86-64/devcontainer.json

 {
+    "name": "TeachOS on x86-64",
     "image": "registry.gitlab.ost.ch:45023/teachos/devcontainers/x86-64:14.2.0",
     "customizations": {
         "vscode": {
             "extensions": [
+                "basdp.language-gas-x86",
+                "ms-python.python",
                 "ms-vscode.cmake-tools",
-                "ms-vscode.cpptools"
+                "ms-vscode.cpptools",
+                "zixuanwang.linkerscript"
             ]
         }
     }