[TIMOB-26327] iOS: Be able to use frameworks from outside the platform/ directory

From recent talks with one of our customers, having to copy frameworks in native modules to platform/ seems to be an unnecessary step these days, because the Xcode-project should be smart enough to locate the frameworks by looking at the FRAMEWORK_SEARCH_PATHS value of their main executable target. This is explicitly important to support CocoaPods (puts the frameworks into Pods/ or Carthage (puts the frameworks to Carthage/Build/). Once this works, we can ideally support CocoaPods and Carthage already. This change needs to be done in the iOS _build.js. The _buildModule.js (responsible to package the module itself) already knows which framework search paths to use.