[Android CHIPTool] Wi-Fi vs Thread provisioning.

[vidhis88]

Problem

Currently, Thread vs Wi-Fi provisioning is embedded inside the Scan QR flow, making it difficult to find.

Summary of Changes

Add distinct buttons to Android app to provision Wi-Fi vs Thread network during CHIP device setup.

Fixes #4081

[andy31415]

We also have #4073 - they seem to be very related (overlapping code even). Could we somehow merge the functionality?

[Damian-Nordic]

Yes, both PRs address the same issue, but in different ways.

This PR introduces a separate flow for Thread devices and a separate button in the main application screen. It still, however, sends dummy Thread credentials during the Rendezvous phase.

My PR (#4073) reuses the existing flow (so the Rendezvous phase is initiated in the same way for both Wi-Fi and Thread devices), but extends the Wi-Fi credentials screen that appears when the Rendezvous session gets to the network provisioning. With my PR the screen contains two tabs and a user may select what kind of network he/she wants to put the accessory device on:

While default Thread settings are provided in the form, they can be overridden, so any Thread settings can be sent to the device.

We may decide which option is preferred, but anyway I think the form for entering Thread credentials from my PR is needed to get rid of those dummy credentials.

[vidhis88]

Updated PR with only Android demo app changes to bring Thread and Wi-Fi provisioning 2 levels up to the app's home page. PTAL.
@andy31415, @BroderickCarlin, @bzbarsky-apple, @chrisdecenzo, @hawk248, @jelderton, @mspang, @rwalker-apple and @saurabhst