jest: set up for coverage - recommended extensions

Author: baob

.vscode/extensions.json

@@ -4,9 +4,10 @@
 
 	// List of extensions which should be recommended for users of this workspace.
 	"recommendations": [
-    "orta.vscode-jest",
-    "andys8.jest-snippets",
-    "dbaeumer.vscode-eslint"
+        "orta.vscode-jest",
+        "ryanluker.vscode-coverage-gutters",
+        "andys8.jest-snippets",
+        "dbaeumer.vscode-eslint"
 	],
 	// List of extensions recommended by VS Code that should not be recommended for users of this workspace.
 	"unwantedRecommendations": [