Fixes #FINCN-326 Create, update, list tellers and Teller Details implemented

[varsvat]

Fixes FINCN-326 and FINCN-327

Creating, Editing, updating Teller functionality Implemented through MVVM architecture. Teller Details Screen has also been implemented. UI tests for various text fields have also been integrated.

Edit: Support for Task management features have also been extended.

This PR adds support for the following functionalities and improvements:

1. Creating Tellers
2. Editing and updating existing Tellers
3. Teller details screen
4. Teller List screen
5. Support for Task management features like closing, reopening, and activating the Tellers.

The UI for all the screens has been tried to keep as similar as possible to maintain uniformity of UI in the app.

https://user-images.githubusercontent.com/53621853/122604338-6d73af00-d093-11eb-9022-80ed1f720fc9.mp4

Task management features:

https://user-images.githubusercontent.com/53621853/122975359-e5521a00-d3b0-11eb-80ce-4b835e7cf367.mp4

Please make sure these boxes are checked before submitting your pull request - thanks!

• [x] Apply the AndroidStyle.xml style template to your code in Android Studio.

• [x] Run the unit tests with ./gradlew check to make sure you didn't break anything.

• [x] If you have multiple commits please combine them into one commit by squashing them.