Fixed Hidden Previous Button in Review Mode

IMPORTANT: All PRs must be linked to an issue (except for extremely trivial and straightforward changes).

Fixes #2516

Description Issue was constraints applied to the buttons. Initial Constraints : [Prev] -> [Next] -> [Submit] [Review] So if submit and next button becomes invisible, prev was hiding below review

Current Constraints : [Prev] -> [Next] -> [Review] -> [Submit]

Type Choose one: Bug fix

Screenshots (if applicable)

Checklist

[x] I have read and acknowledged the Code of conduct.
[x] I have read the Contributing page.
[x] I have signed the Google Individual CLA, or I am covered by my company's Corporate CLA.
[ ] I have discussed my proposed solution with code owners in the linked issue(s) and we have agreed upon the general approach.
[x] I have run ./gradlew spotlessApply and ./gradlew spotlessCheck to check my code follows the style guide of this project.
[x] I have run ./gradlew check and ./gradlew connectedCheck to test my changes locally.
[x] I have built and run the demo app(s) to verify my change fixes the issue and/or does not break the demo app(s).

google / android-fhir

Fixed Hidden Previous Button in Review Mode #2523