Change location of iOS build cache directory to ~/Library/Caches/ (#22688)

Summary:
Instead of using ~/.rncache use the special Caches directory designed for caching files. This fixes #21780.

Changelog:
----------

[iOS] [Changed] - Moved iOS build cache directory from ~/.rncache to ~/Library/Caches/com.facebook.ReactNativeBuild
Pull Request resolved: https://github.com/facebook/react-native/pull/22688

Differential Revision: D13817171

Pulled By: cpojer

fbshipit-source-id: af03dda66f9d49f4fe88bd050b359ccb7abb889a

scripts/ios-install-third-party.sh

@@ -4,14 +4,18 @@
 # This source code is licensed under the MIT license found in the
 # LICENSE file in the root directory of this source tree.
 
-cachedir="$HOME/.rncache"
+if [ -d "$HOME/.rncache" ]; then
+  cachedir="$HOME/.rncache" # react-native 0.57.8 and older
+else
+  cachedir="$HOME/Library/Caches/com.facebook.ReactNativeBuild"
+fi
 mkdir -p "$cachedir"
 
 function file_fail () {
     cachefile=$1
     msg=$2
 
-    echo "$msg.  Debug info:" 2>&1
+    echo "$msg. Debug info:" 2>&1
     ls -l "$cachefile" 2>&1
     shasum "$cachefile" 2>&1
     exit 1
@@ -29,7 +33,7 @@ function fetch_and_unpack () {
     while true; do
         if [ -f "$cachedir/$file" ]; then
            if shasum -p "$cachedir/$file" |
-              awk -v hash="$hash" '{exit $1 != hash}'; then
+               awk -v hash="$hash" '{exit $1 != hash}'; then
                break
            else
                echo "Incorrect hash:" 2>&1