Refactor package.json handling in pre-publish script to create a private copy and update main package.json

scripts/prepare-package-json.sh

@@ -6,4 +6,5 @@ set -o pipefail
 set -x
 
 jq '{name, version, type, dependencies, module, main, types, exports, publishConfig}' package.json > package.json.tmp
-mv package.json.tmp dist/package.json
+cp package.json package.json.private
+mv package.json.tmp package.json