exclude .bazel and node_modules from Pylance indexing

Should hopefully prevent VS Code from burning CPU needlessly.
Pyright is not intended to be used outside of VS Code, as a lot of our
legacy code depends on optionals not being checked strictly.

Yet another tool that pollutes the root folder. :-(

pyrightconfig.json

@@ -0,0 +1,3 @@
+{
+    "exclude": ["**/node_modules", ".bazel"]
+}