ci: add Game CI (#21)

.vscode/extensions.json

@@ -1,3 +1,9 @@
 {
-  "recommendations": ["visualstudiotoolsforunity.vstuc"]
+  "recommendations": [
+    "editorconfig.editorconfig",
+    "jebbs.plantuml",
+    "visualstudiotoolsforunity.vstuc",
+    "ms-dotnettools.csharp",
+    "ms-dotnettools.csdevkit"
+  ]
 }

.vscode/settings.json

@@ -1,3 +1,10 @@
 {
-  "dotnet.defaultSolution": "GeometryDash.sln"
+  "editor.bracketPairColorization.enabled": true,
+  "editor.wordWrap": "on",
+  "[csharp]": {
+    "editor.tabSize": 4,
+    "editor.formatOnSave": true,
+    "editor.formatOnType": true
+  },
+  "omnisharp.useModernNet": false
 }