[Fragment-Migration] Sync Login Screen to use Fragments instead of activities

[criticalAY]

Purpose / Description

• Blocked by: feat: landscape resource quantifier for sync account #17949
• Migrates the MyAccount, Login Activities to fragments

Approach

• Create a new activity to handle the logged in and !LoggedIn situation as we are starting the fragments from preference screen
• Two different fragments to handle the two situations i.e. Logged in and vice versa
• Use view model for Login fragment and handles the changes via the viewmodel
• remove the old code
• update existing test (one more test file is needed for Logged in UI which I deleted)

How Has This Been Tested?

Test On API 35 Google emulator:
I am uploading all the screenshots and videos to drive as it would be too much for the template

https://drive.google.com/drive/folders/1lYg4rz-SdFhwb-3rlQIs5aUwnjwJgDiK?usp=sharing

Checklist

Please, go through these checks before submitting the PR.

• You have a descriptive commit message with a short title (first line, max 50 chars).
• You have commented your code, particularly in hard-to-understand areas
• You have performed a self-review of your own code
• UI changes: include screenshots of all affected screens (in particular showing any new or changed strings)
• UI Changes: You have tested your change using the Google Accessibility Scanner

[mikehardy]

Please test locally before pushing

[BrayanDSO]

How Has This Been Tested?
Test On API 35

Quoting the PR template:

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration (SDK version(s), emulator or physical, etc)

So please do that. Your description isn't enough for anyone to reproduce or trust your testing process. A video would be even better.

[criticalAY]

I have uploaded all the SSs to drive along with few test videos

[BrayanDSO]

Haven't reviewed all of it, but it looks good overall

[BrayanDSO]

In the future, we ideally should rely less on AccountActivity and be able to launch the fragment anywhere.

[BrayanDSO]

If the parent activity doesn't have android:configChanges="orientation", this doesn't work.

I get that having a separate layout file just for that is a lot of boilerplate, so I'm fine with the current approach.

But do note at the class docs that the parent activity needs to listen to "orientation" configuration changes to work properly, and note why a separate layout file isn't being used.