Workspaces/Submodules: top-level `pnpm i` doesn't install deps of protobuf.js

[egasimus]

Gotta move packages/cosmjs-esm/protobuf.js to packages/protobuf.js but then cosmjs-esm becomes dependent on the workspace. But... there is already a similar case in toolbox/ensuite/ubik, so might as well. (Gotta try first if adding protobuf to /pnpm-workspace.yaml won't work on a fresh checkout though.)