Integrate arethetypeswrong (#565)

Fixes #456 

This integrates the
[`arethetypeswrong`](https://github.com/arethetypeswrong/arethetypeswrong.github.io/tree/main)
CLI tool for checking types in published packages. It also adds the call
to lint the types in CI that it is easy to spot regressions.

Makefile

@@ -193,8 +193,11 @@ test-ts-compat: $(GEN)/protobuf-test node_modules
 	done
 
 .PHONY: lint
-lint: node_modules $(BUILD)/protobuf $(BUILD)/protobuf-test $(BUILD)/protobuf-conformance $(GEN)/protobuf-bench $(GEN)/protobuf-example ## Lint all files
+lint: node_modules $(BUILD)/protobuf $(BUILD)/protobuf-test $(BUILD)/protobuf-conformance $(BUILD)/protoplugin $(GEN)/protobuf-bench $(GEN)/protobuf-example ## Lint all files
 	npx eslint --max-warnings 0 .
+	@# Check type exports on npm packages to verify they're correct
+	npm run -w packages/protobuf attw
+	npm run -w packages/protoplugin attw
 
 .PHONY: format
 format: node_modules $(BIN)/git-ls-files-unstaged $(BIN)/license-header ## Format all files, adding license headers