[ios] Prefer xcbuild action to sh("xcodebuild ...") (#2427)
[ios] Prefer xcbuild action to sh("xcodebuild ...") (#2427)

* [ios] Prefer xcbuild action to sh("xcodebuild ...")

* [ios] Correct simulator build directory message

exponent/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponentjs/exponent,exponent/exponent,exponent/exponent,exponentjs/exponent,exponentjs/exponent,exponentjs/exponent,exponentjs/exponent,exponent/exponent