Release Playground Dummy (VS Code)

A dummy VS Code extension. It exists only to exercise the Release Manager vscode-extension upload path and the VS Code Marketplace push end-to-end. It registers a single no-op command (Release Playground: Ping) and does nothing else useful.

Note: the VS Code Marketplace has no private/unlisted option, so once pushed upstream this extension is publicly visible under the ReleaseManagerCiCd publisher. It is clearly marked as a dummy.