Merge Unified Login & Signup changes from WPAndroid

[renanferrari]

This PR merges the changes from the Unified Login & Signup project in WPAndroid.

Here's a list of all included PRs:

• Functional changes

  • Create Sign-Up From Login functionality for Email + Magic Link method
  • Create Sign-Up From Login functionality for Google Sign-In method
  • Login with site address from the Prologue screen

• UI changes

  • Prologue screen UI update
  • Epilogue screen UI update
  • Login library theme and styles update
  • Login library screen layouts update
  • Add Signup Confirmation screen
  • Disable primary buttons on empty fields
  • Fix theming-related issues
  • Fix issues with Gravatar placeholder
  • Update WordPress-Utils library version
  • Replace temporary GravatarUtils from the Login library with the updated one from the Utils library

• Event tracking changes

  • Unified login tracking 1 - Screens
  • Unified login failure tracking
  • Add click tracking to unified login and signup flow
  • Add tracking to Signup Confirmation screen
  • Signup: Add source property to account creation event

The most impactful changes are the ones related to the UI, as both the theme and styles used by the library got a major overhaul. Those changes were reviewed by both WordPress and WooCommerce teams at the time.

Here's a summary of the main breaking changes to watch out for:

• The theme used by the library as well as the styles have all been renamed and updated.
• The structure used by resources (themes, styles, colors) has also been updated.
• A new screen has been added (Signup Confirmation Screen) and LoginListener was updated accordingly.
• New tracking events have been added and LoginAnalyticsListener was updated accordingly.
• Most screens have new layouts and the base layout used by all of them has also been updated.
• LoginEmailFragment is the only screen that has kept both its old and new layouts, which can be switched by using the shouldUseNewLayout flag.
• The library now depends on the version 1.26 of the Utils library.

[planarvoid]

@renanferrari renanferrari requested review from khaykov, planarvoid and AmandaRiu and removed request for khaykov and planarvoid 3 days ago

Github got confused and I'm not sure whether I should review this PR or not :-). It's in the list of my "Review requests" but I'm not listed as a "Reviewer". Is @AmandaRiu enough @renanferrari ?

[renanferrari]

Sorry for the confusion, @planarvoid! I had initially requested a review from you and @khaykov but then I talked to the Woo team and decided it was better to leave it to @AmandaRiu, as these changes are most relevant to them.

[AmandaRiu]

@renanferrari did an unofficial review of the changes as they pertain to woo-mobile and all looks good. It will be some work for sure, but thanks to you it will be less work 😄. Removing myself as a reviewer since I'm not officially reviewing this PR as discussed in Slack.

[renanferrari]

@AmandaRiu Thank you! Your "unofficial review" was actually the only thing pending for this PR, as everything else was already tested in WPAndroid 🙂 Since it also looks good on your side, I'm gonna go ahead and merge it.