CI-915 Keep The Login Pipeline Alive Across Rotation

[OrangeAndGreen]

CI-915

Stacked on PR #3881 that fixes the initial crash when trying to show the dialog on resume.

Product Description

Rotating the device during login no longer breaks it. Previously, a rotation mid-sync aborted the data pull, left the progress dialog frozen part-way, and never completed or failed the login — the user had to force-quit and start over.

Technical Summary

• The login pipeline was launched on LoginActivity's lifecycleScope, which is cancelled at onDestroy
  • A rotation therefore cancelled the coroutine
  • And SyncOperations cancelled DataPullTask from its invokeOnCancellation handler
• So the restore was aborted, no result was ever delivered, and the dialog was orphaned

Pre-2.64 this was handled by the task-connector framework, but the headless login engine opted out of that and uses HeadlessTaskConnector.connectTask instead.

This PR introduces LoginViewModel to own the job in viewModelScope so it can survive configuration changes.

A couple extra notes:

• currentLoginPhase stayed in LoginActivity so it gets reset on activity recreation and is used to show the dialog again
• The result is single-use so complete login doesn't get replayed if the screen rotates after the job completes

Safety Assurance

Safety story

• I verified that I am no longer able to reproduce either of the issues before related to sync during login:

1. App does not crash on resume if sent to background during sync
2. Sync dialog is not orphaned if the screen is rotated during sync

• Did some general usage testing around the login process and made sure everything appears to work normally

Automated test coverage

Four tests added to LoginProgressDialogLifecycleTest:

• rotation keeps the login running and puts its dialog back
• stop button cancels a pipeline that survived rotation
• a consumed result is not redelivered after rotation
• a finished login leaves no dialog behind on rotation

[OrangeAndGreen]

Suggested Review Order

• app/src/org/commcare/login/LoginController.kt — the deleted start() bridge; the bug's origin, and smallest context to load first
• app/src/org/commcare/login/LoginViewModel.kt — its replacement and the new owner of the job; the comments explain the three non-obvious constraints
• app/src/org/commcare/activities/LoginActivity.java — the consumer: two observers replace the two activity-bound callbacks
• app/unit-tests/src/org/commcare/activities/LoginProgressDialogLifecycleTest.kt — the four new rotation tests pin the behaviour described above
• RELEASES.md — release note and QA steps; each is its own commit

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 28.14%. Comparing base (14fec4a) to head (a8702ec).

Additional details and impacted files

@@                             Coverage Diff                             @@
##             CI-915-progress-dialog-state-loss-fix    #3890      +/-   ##
===========================================================================
+ Coverage                                    27.92%   28.14%   +0.21%     
- Complexity                                    4885     4923      +38     
===========================================================================
  Files                                          987      988       +1     
  Lines                                        58969    58996      +27     
  Branches                                      7022     7023       +1     
===========================================================================
+ Hits                                         16465    16602     +137     
+ Misses                                       40525    40405     -120     
- Partials                                      1979     1989      +10     

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