NSURLConnection sendSynchronousRequest is deprecated since iOS 9. Replace the
method by whjat's currently on RN master, which implements a modern alternative.

This new version comes with an updated JSC runtime, so we no longer need to
depend on the updated version ourselves.

- cleanup
- API simplification (single loadURL method)
- JitsiMeet singleton for linking helpers and globals
- Linking moved to app

On iOS, if the app is closed the startup options are only passed as the
`launchOptions` dictionary of `applicationDidFinishLaunching`. Thus add a helper
method to be called from there by embedding applications so we can copy that
dictionary.

1. Aligns the project structure of Jitsi Meet SDK for iOS with that for
   Android for better comprehension.

2. The command `react-native run-ios` uses the last Xcode project or
   workspace in the list of these sorted in alphabetical order. Which
   limits our freedom in naming. Thus having only an Xcode project in
   the root directory of the iOS project structure gives us back the
   freedom in naming.

3. Allows the Podspec to work for the app project in addition to the sdk
   project because we need Crashlytics in the app which is integrated
   via Cocoapods as well.

4. Further removes references to JitsiKit in the source code for the
   sake of consistent naming.

Ladies and gentlemen, allow me to introduce you to Jitsi Meet SDK for iOS, the
mobile SDK which powers Jitsi Meet.

The goal is to encapsulate the entire React Native app into a framework / SDK
and offer an API for native (ObjC or Swift) applications to embed the Jitsi
conferencing experience.

While React Native can be embedded in native applications, I don't think it was
designed to be embedded as part of a framework, hidden away from the application
using it. This surfaced as a number of issues which had to be addressed
specifically due to our use-case:

- Universal / deep linking needed to be wrapped to avoid the embedding app from
  linking with RN.
- The bundle URL had to be manually constructed, since RN considers that all
  resources are in the main bundle, but in case of a framework that is not the
  case.
- Custom fonts had to be manually loaded, since UIAppFonts doesn't work on the
  framework's Info.plist file.
- The RN packager has to be manually triggered since the React project will no
  longer do it for us.
- Custom App Transport Security rules were added since the builtin way to do it
  modifies the framework's Info.plist, which is useless in this case.

At this stage, the Jitsi Meet application is just a small single view
application which uses the Jitsi Meet SDK to create a single view which
represents the entire application. Events and external conference handling are
forthcoming.