Change irrelevant Products path in ./local-cli/runIOS/runIOS.js

Summary:
https://github.com/facebook/react-native/issues/7308
and many of the same

Seems like xcode cli tool isn't create ./build directory any more but place Products
right inside ./Build (may check while creating single view ios application
in XCode)

* edit hardcoded path to {appName}.app

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Command `$ react-native run-ios` is often lead to `Entry, ":CFBundleIdentifier", Does Not Exist`
I find out how to fix it in current version of RN and Xcode cli tools

Just try to do `$ react native init {appName}` and then `$ react native run-ios` if everything fine it means my approach is right :)

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  CATEGORY
[----------]        TYPE
[ CLI      ]   [-------------]      LOCATION
[ DOCS     ]   [ BREAKING    ]   [-------------]
[ GENERAL  ]   [ BUGFIX      ]   [-{Component}-]
[ INTERNAL ]   [ ENHANCEMENT ]   [ {File}      ]
[ IOS      ]   [ FEATURE     ]   [ {Directory} ]   |-----------|
[ ANDROID  ]   [ MINOR       ]   [ {Framework} ] - | {Message} |
[----------]   [-------------]   [-------------]   |-----------|

[CATEGORY] [TYPE] [LOCATION] - MESSAGE

 EXAMPLES:

 [IOS] [BREAKING] [FlatList] - Change a thing that breaks other things
 [ANDROID] [BUGFIX] [TextInput] - Did a thing to TextInput
 [CLI] [FEATURE] [local-cli/info/info.js] - CLI easier to do things with
 [DOCS] [BUGFIX] [GettingStarted.md] - Accidentally a thing/word
 [GENERAL] [ENHANCEMENT] [Yoga] - Added new yoga thing/position
 [INTERNAL] [FEATURE] [./scripts] - Added thing to script that nobody will see
-->
Closes https://github.com/facebook/react-native/pull/17963

Differential Revision: D7014984

Pulled By: hramos

fbshipit-source-id: da62f130e6ebf7d3acd09d36525838d5c9684e75