Dev Container extensions (#23)

* Added extensions

* Cut down on extensions

* Added extension

* Removed pull requests extension

* Added workspace recommendation

* Added powershell feature

* Fixed powershell version

* Updated powershell version and added extension

* Updated to latest powershell

.devcontainer/devcontainer.json

@@ -14,6 +14,26 @@
     },
     "ghcr.io/devcontainers/features/docker-in-docker:2": {
       "version": "20.10"
+    },
+    "ghcr.io/devcontainers/features/powershell:1": {
+      "version": "7.3"
     }
+},
+"customizations": {
+	"vscode": {
+		"extensions": [
+			"DavidAnson.vscode-markdownlint",
+			"eamodio.gitlens",
+			"github.vscode-github-actions",
+			"GitHub.codespaces",
+			"jebbs.plantuml",
+			"ms-python.isort",
+			"ms-vscode-remote.remote-containers",
+			"ms-vscode.cpptools-themes",
+      "ms-vscode.PowerShell",
+			"tomoki1207.pdf",
+			"yzhang.markdown-all-in-one"
+		]
 	}
 }
+}

.vscode/extensions.json

@@ -0,0 +1,5 @@
+{
+    "recommendations": [
+        "github.vscode-pull-request-github"
+    ]
+}