feature/9452-ClaimFileUploadEmbeddedScreens

[alexandec]

Description of Change

Modify the Claim File Request and Submit Evidence flows to function as nested child screens inside a single FullScreenSubtask. This PR creates a new pattern we can use for any similar multi-step subtask.

PR includes:

• Creation of a new MultiStepSubtask template which wraps FullScreenSubtask
• Creation of a UseSubtaskProps hook and associated context allowing child screens to set props on the parent FullScreenSubtask (buttons, etc)
• Accommodation of shared screens between the File Request and Submit Evidence nav stacks

Screenshots/Video

File Request Before:

original.mp4

File Request After:

refactored-title.mp4

Testing

• Tested on iOS
• Tested on Android

Reviewer Validations

• Coordinate with/bring in the @liztownd work done on the top part of the Travel Pay subtask screen flow. She has a successful solution within this flow.
• Copy the behavior within Messages > Start new message
• “Freeze” top nav bar, so that screen content changes between screens, but top nav appears fixed. (See behavior on first screen on scroll)
• VQA with designer (approval in Slack thread)

PR Checklist

Reviewer: Confirm the items below as you review

• PR is connected to issue(s)
• Tests are included to cover this change (when possible)
• No magic strings (All string unions follow the Union -> Constant type pattern)
• No secrets or API keys are checked in
• All imports are absolute (no relative imports)
• New functions and Redux work have proper TSDoc annotations

For QA

Run a build for this branch