Add extensibility point on react-native-xcode.sh script

Summary:
Original pull request: #12863

Useful for generating source maps, for example.

Feature parity with Android, that already have this extensibility point on `build.gradle`:
```
project.ext.react = [
    extraPackagerArgs: [...]
]
```

Xcode > Build Phases > Bundle React Native code and Images
```
export NODE_BINARY=node
export EXTRA_PACKAGER_ARGS="--sourcemap-output ${SRCROOT}/build/main.jsbundle.map"
../node_modules/react-native/scripts/react-native-xcode.sh
```

[IOS] [FEATURE] [./react-native-xcode.sh] - Added $EXTRA_PACKAGER_ARGS extensibility point
Closes https://github.com/facebook/react-native/pull/16933

Differential Revision: D6771709

Pulled By: yungsters

fbshipit-source-id: a33614b45b1e3537daeb31504fdd3a402dc70ff0

scripts/react-native-xcode.sh

@@ -1,129 +0,0 @@
-#!/bin/bash
-# Copyright (c) 2015-present, Facebook, Inc.
-# All rights reserved.
-#
-# This source code is licensed under the BSD-style license found in the
-# LICENSE file in the root directory of this source tree. An additional grant
-# of patent rights can be found in the PATENTS file in the same directory.
-
-# Bundle React Native app's code and image assets.
-# This script is supposed to be invoked as part of Xcode build process
-# and relies on environment variables (including PWD) set by Xcode
-
-if [[ "$SKIP_BUNDLING" ]]; then
-  echo "SKIP_BUNDLING enabled; skipping."
-  exit 0;
-fi
-
-case "$CONFIGURATION" in
-  *Debug*)
-    if [[ "$PLATFORM_NAME" == *simulator ]]; then
-      if [[ "$FORCE_BUNDLING" ]]; then
-        echo "FORCE_BUNDLING enabled; continuing to bundle."
-      else
-        echo "Skipping bundling in Debug for the Simulator (since the packager bundles for you). Use the FORCE_BUNDLING flag to change this behavior."
-        exit 0;
-      fi
-    else
-      echo "Bundling for physical device. Use the SKIP_BUNDLING flag to change this behavior."
-    fi
-
-    DEV=true
-    ;;
-  "")
-    echo "$0 must be invoked by Xcode"
-    exit 1
-    ;;
-  *)
-    DEV=false
-    ;;
-esac
-
-# Path to react-native folder inside node_modules
-REACT_NATIVE_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
-
-# Xcode project file for React Native apps is located in ios/ subfolder
-cd "${REACT_NATIVE_DIR}"/../..
-
-# Define NVM_DIR and source the nvm.sh setup script
-[ -z "$NVM_DIR" ] && export NVM_DIR="$HOME/.nvm"
-
-# Define entry file
-if [[ -s "index.ios.js" ]]; then
-  ENTRY_FILE=${1:-index.ios.js}
-else
-  ENTRY_FILE=${1:-index.js}
-fi
-
-if [[ -s "$HOME/.nvm/nvm.sh" ]]; then
-  . "$HOME/.nvm/nvm.sh"
-elif [[ -x "$(command -v brew)" && -s "$(brew --prefix nvm)/nvm.sh" ]]; then
-  . "$(brew --prefix nvm)/nvm.sh"
-fi
-
-# Set up the nodenv node version manager if present
-if [[ -x "$HOME/.nodenv/bin/nodenv" ]]; then
-  eval "$("$HOME/.nodenv/bin/nodenv" init -)"
-fi
-
-[ -z "$NODE_BINARY" ] && export NODE_BINARY="node"
-
-[ -z "$CLI_PATH" ] && export CLI_PATH="$REACT_NATIVE_DIR/local-cli/cli.js"
-
-[ -z "$BUNDLE_COMMAND" ] && BUNDLE_COMMAND="bundle"
-
-if [[ -z "$BUNDLE_CONFIG" ]]; then
-  CONFIG_ARG=""
-else
-  CONFIG_ARG="--config $(pwd)/$BUNDLE_CONFIG"
-fi
-
-nodejs_not_found()
-{
-  echo "error: Can't find '$NODE_BINARY' binary to build React Native bundle" >&2
-  echo "If you have non-standard nodejs installation, select your project in Xcode," >&2
-  echo "find 'Build Phases' - 'Bundle React Native code and images'" >&2
-  echo "and change NODE_BINARY to absolute path to your node executable" >&2
-  echo "(you can find it by invoking 'which node' in the terminal)" >&2
-  exit 2
-}
-
-type $NODE_BINARY >/dev/null 2>&1 || nodejs_not_found
-
-# Print commands before executing them (useful for troubleshooting)
-set -x
-DEST=$CONFIGURATION_BUILD_DIR/$UNLOCALIZED_RESOURCES_FOLDER_PATH
-
-if [[ "$CONFIGURATION" = "Debug" && ! "$PLATFORM_NAME" == *simulator ]]; then
-  PLISTBUDDY='/usr/libexec/PlistBuddy'
-  PLIST=$TARGET_BUILD_DIR/$INFOPLIST_PATH
-  IP=$(ipconfig getifaddr en0)
-  if [ -z "$IP" ]; then
-    IP=$(ifconfig | grep 'inet ' | grep -v ' 127.' | cut -d\   -f2  | awk 'NR==1{print $1}')
-  fi
-
-  if [ -z ${DISABLE_XIP+x} ]; then
-    IP="$IP.xip.io"
-  fi
-
-  $PLISTBUDDY -c "Add NSAppTransportSecurity:NSExceptionDomains:localhost:NSTemporaryExceptionAllowsInsecureHTTPLoads bool true" "$PLIST"
-  $PLISTBUDDY -c "Add NSAppTransportSecurity:NSExceptionDomains:$IP:NSTemporaryExceptionAllowsInsecureHTTPLoads bool true" "$PLIST"
-  echo "$IP" > "$DEST/ip.txt"
-fi
-
-BUNDLE_FILE="$DEST/main.jsbundle"
-
-$NODE_BINARY $CLI_PATH $BUNDLE_COMMAND \
-  $CONFIG_ARG \
-  --entry-file "$ENTRY_FILE" \
-  --platform ios \
-  --dev $DEV \
-  --reset-cache \
-  --bundle-output "$BUNDLE_FILE" \
-  --assets-dest "$DEST"
-
-if [[ $DEV != true && ! -f "$BUNDLE_FILE" ]]; then
-  echo "error: File $BUNDLE_FILE does not exist. This must be a bug with" >&2
-  echo "React Native, please report it here: https://github.com/facebook/react-native/issues"
-  exit 2
-fi