Rework ExampleApp

[mpiechocki]

Existing example app is too complicated and thus not very helpful. I would like to rework the example to something more readable and simple.

Here's the plan, for now:

1. Get rid of existing ExampleApp ;)
2. Add a catalyst app, with targets: iOS 13.0, macOS 10.15 2.1. App will be divided to two parts: Central and Peripheral 2.1.1 Central part will let the user enter service and characteristics uuids and connect to the first found peripheral with those. Then it will subscribe to the updates of the characteristics (which value will be a simple Integer). 2.1.2 Peripheral part will let user enter service and characteristics uuids and then start advertising them. Then user will be able to enter a new value for a characteristic and update it.

This will enable everyone new to the topic of RxBluetoothKit to: 1) learn the simplest use-case which actually leverages the power of Rx and RxBluetoothKit in specific, 2) Use their iOS device and a mac device to create a connection between them (not everyone has a BLE sensor at home).

P.S. As it's a Rx library, I won't use SwiftUI as it would probably only make subject (which is a simple code using RxBluetoothKit) less readable.

[mpiechocki]

Suggested further actions:

• Add a feature to scan all the nearby peripherals and select the one to connect to.