[WIP] Fix Play services install and sign in flow

[gino-m]

Replaces ephemeral navigation requests with a "main UI state" which gets applied at start up. This patch resolves existing issues, but there are likely several race conditions lurking due to complexity of the startup/install flow. We should revisit the design on this flow to make it easier to understand and to avoid cancellation exceptions or duplicate side effects (#2923).

Fixes #2919 by restore UI state on on resume.
Fixes #2783

[shobhitagarwal1612]

Can we make it Timber.e?

[shobhitagarwal1612]

Can we cleanup debug logs if they aren't needed anymore?

[shobhitagarwal1612]

Same as above

[gino-m]

@shobhitagarwal1612 @anandwana001 This actually won't work - collecting the so-called "MainUiState" on resume will navigate the user away from their current screen in many cases (ToS, survey list, etc), since those screens are not represented in the UiState.

Filed #2934 to track, moving back to Draft :/

[gino-m]

Main is currently navigating to the wrong target on config change. Instead, allow each Fragment to maintain its own state and navigation actions by moving sign-in flow logic out of Main and into StartUp, SignIn and TermsOfService as follows:

• StartUp will direct to the Home if already signed in, SignIn if not.
• SignIn will direct to TermsOfService if available, otherwise to SurveySelector.
• TermsOfService will direct to Home.
• Main will navigate to SignIn on sign-out.

[gino-m]

Main is currently navigating to the wrong target on config change. Instead, allow each Fragment to maintain its own state and navigation actions by moving sign-in flow logic out of Main and into StartUp, SignIn and TermsOfService as follows:

• StartUp will direct to the Home if already signed in, SignIn if not.
• SignIn will direct to TermsOfService if available, otherwise to SurveySelector.
• TermsOfService will direct to Home.
• Main will navigate to SignIn on sign-out.

@shobhitagarwal1612 @anandwana001 Do you want to want to pick these up?