Fixed script for Packager.sh in RNTester (facebook#36582)

Summary:
Pull Request resolved: facebook#36582

This change should fix the path to run packager.sh directly from Xcode, this was broken after the Monorepo work.

## Changelog:
[internal] - update path to run packager.sh

Reviewed By: huntie, hoxyq

Differential Revision: D44292167

fbshipit-source-id: 90e0291aa7a15189c72cae99c5d38c84c7243a80

Author: cipolleschi

packages/react-native/scripts/packager.sh

@@ -14,11 +14,6 @@ PROJECT_ROOT=${PROJECT_ROOT:-"$THIS_DIR/../../.."}
 # shellcheck disable=SC1090
 source "${THIS_DIR}/node-binary.sh"
 
-# When running react-native tests, react-native doesn't live in node_modules but in the PROJECT_ROOT
-if [ ! -d "$THIS_DIR/../../../node_modules/react-native" ];
-then
-  PROJECT_ROOT="$THIS_DIR/../../.."
-fi
 # Start packager from PROJECT_ROOT
 cd "$PROJECT_ROOT" || exit
 "$NODE_BINARY" "$REACT_NATIVE_ROOT/cli.js" start --custom-log-reporter-path "$THIS_DIR/packager-reporter.js" "$@"

packages/rn-tester/RNTesterPods.xcodeproj/project.pbxproj

@@ -644,7 +644,7 @@
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 			shellPath = /bin/sh;
-			shellScript = "set -x\n\nexport RCT_METRO_PORT=\"${RCT_METRO_PORT:=8081}\"\necho \"export RCT_METRO_PORT=${RCT_METRO_PORT}\" > \"${SRCROOT}/../react-native/scripts/.packager.env\"\nif [ -z \"${RCT_NO_LAUNCH_PACKAGER+xxx}\" ] ; then\n  if nc -w 5 -z localhost ${RCT_METRO_PORT} ; then\n    if ! curl -s \"http://localhost:${RCT_METRO_PORT}/status\" | grep -q \"packager-status:running\" ; then\n      echo \"Port ${RCT_METRO_PORT} already in use, packager is either not running or not running correctly\"\n      exit 2\n    fi\n  else\n    open -n \"$SRCROOT/../react-native/scripts/launchPackager.command\" || echo \"Can't start packager automatically\"\n  fi\nfi\n";
+			shellScript = "set -x\n\n# RN-Tester does not have an iOS directory. The PROJECT_ROOT should \n# point to the folder where the `metro.config.js` file lives.\nexport PROJECT_ROOT=$(pwd)\nexport RCT_METRO_PORT=\"${RCT_METRO_PORT:=8081}\"\necho \"export RCT_METRO_PORT=${RCT_METRO_PORT}\" > \"${SRCROOT}/../react-native/scripts/.packager.env\"\nif [ -z \"${RCT_NO_LAUNCH_PACKAGER+xxx}\" ] ; then\n  if nc -w 5 -z localhost ${RCT_METRO_PORT} ; then\n    if ! curl -s \"http://localhost:${RCT_METRO_PORT}/status\" | grep -q \"packager-status:running\" ; then\n      echo \"Port ${RCT_METRO_PORT} already in use, packager is either not running or not running correctly\"\n      exit 2\n    fi\n  else\n    open -n \"$SRCROOT/../react-native/scripts/launchPackager.command\" || echo \"Can't start packager automatically\"\n  fi\nfi\n";
 			showEnvVarsInLog = 0;
 		};
 		68CD48B71D2BCB2C007E06A9 /* Build JS Bundle */ = {