Add -all option for 'yarn clean' to help with node_modules issues

utils/clean.sh

@@ -13,11 +13,30 @@ MYPATH=$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )
 # ROOT is the root directory of our project.
 ROOT="$MYPATH/.."
 
-pushd "$ROOT"
+pushd "$ROOT" >/dev/null 2>&1
+
+CLEAN_ALL=false
+while [[ $# -gt 0 ]]; do
+  case $1 in
+    -a|--all)
+      CLEAN_ALL=true
+      shift # past argument
+      ;;
+    *)
+      echo "Unknown option: $1"
+      exit 1
+      ;;
+  esac
+done
 
 rm -rf packages/*/dist
 rm -rf .nyc_output/
 rm -rf coverage/
 rm -rf cypress/
 rm -rf packages/*/*.tsbuildinfo
 rm -rf storybook-static/
+
+if [[ "$CLEAN_ALL" == "true" ]]; then
+    echo "Removing node_modules directories. You'll need to 'yarn install' after this."
+    find . -name node_modules -and -type d -prune -exec rm -rf '{}' \;
+fi