DEV: Move vscode config files to `.vscode-sample` directory (#11943)

We want to allow developers to customize their own vscode environment.
Including launch.json/tasks.json files in the repository makes this very
difficult.

These were originally added for GitHub codespaces. Once codespaces is
more widely available, we can look into automatically copying the
`.vscode-sample` directory to `.vscode` when the codespace boots.

.gitignore

@@ -137,10 +137,8 @@ node_modules
 # ignore generated api documentation files
 openapi/*
 
-# ignore custom VSCode config files
-.vscode/*
-!.vscode/launch.json
-!.vscode/tasks.json
+# ignore VSCode config files
+.vscode
 
 # ignore direnv
 .envrc