Auto discover Rust tests

rust-analyzer can tell VS Code which tests exist. But in combination with Bazel this is currently hardly useful. Tests can be executed, but not debugged, which mostly nullifies having the tests in VS Code.

Author: lurtz

src/s-core-devcontainer/.devcontainer/devcontainer.json

@@ -80,6 +80,7 @@
                     "--experimental_enable_label_completions"
                 ],
                 "C_Cpp.intelliSenseEngine": "disabled",
+                "rust-analyzer.testExplorer": true,
                 "tasks": {
                     "version": "2.0.0",
                     "tasks": [