Also, stop bundling WebRTC, it's now a dependency in CocoaPods.

Swift has a longstanding bug where a framework and a type cannot be named the
same. We have somehow managed to not run into this, but it now seems to be
hitting us.

Since this is a breaking change, this starts the road for SDK 3.0.

It can help catch very weird bugs which are only triggered after a reset.

This makes it possible to compile the SDK with Xcode 10 and 11. The problem is
that the Google SDK (used for sign-in) is compiled with Xcode 11. This avoids
the issue.

People run these in their own checkout and will run into problems because
tagging will fail.

Before, Jitsi Meet (the app) would only link with JitsiMeet.framework, which in
turn embedded WebRTC.framework. While possible, Apple doesn't allow apps with
nested frameworks to be submitted to the store. Now the app will link with
WebRTC.framework directly so there is no framework nesting.

A potential improvement here is to build WebRTC as a static library so it can
then be embedded in JitsiMeet.framework and completely hidden from the app.

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.