MBL-1232: Unify and verify sign up/log in buttons

[Arkariang]

📲 What

• Unified buttons, Log in with email and Sign up now happen on the web formulary after OAuth2.0

👀 See

| Before 🐛 | After 🦋 |
FF ON

FF OFF

| | |

📋 QA

• With feature flag on, you will see only one button for sign up or log in
• With feature flag off, you will see the old flow with two separated buttons to log in with email and sign up

Story 📖

MBL-1232

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 85.71429% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 73.88%. Comparing base (925af00) to head (033e40f).

Files	Patch %	Lines
...ter/ui/activities/compose/login/LoginToutScreen.kt	86.95%	2 Missing and 1 partial ⚠️
...a/com/kickstarter/viewmodels/LoginToutViewModel.kt	80.00%	1 Missing ⚠️

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #1961   +/-   ##
=========================================
  Coverage     73.87%   73.88%           
  Complexity     1979     1979           
=========================================
  Files           347      347           
  Lines         19881    19886    +5     
  Branches       2758     2755    -3     
=========================================
+ Hits          14688    14692    +4     
- Misses         3578     3580    +2     
+ Partials       1615     1614    -1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

[leighdouglas]

🎉