General: Relocate back buttons for deep navigation pages

[Bofan-Zhu]

Checklist

General

• I tested all changes and their related features with all corresponding user types.
• I chose a title conforming to the naming conventions for pull requests.

Motivation and Context

All buttons are currently placed on the bottom left. This should only be the case for navigating e.g. within forms but not for deep navigation.

Description

This PR:

• adds a reusable back button component
• replaces the back buttons on deep navigation pages with the reusable back button component
• moves saving state of email template to the top to increase visibility

Steps for Testing

Prerequisites:

1. Log in to TumApply as Professor/Applicant
2. Check that buttons on the pages which cannot be accessed via sidebar are located at the top left

Review Progress

Code Review

• Code Review 1

Manual Tests

• Test 1

Screenshots

[github-actions]

📊 Client Test Coverage Too Low

🔍 View coverage locally:

npm run test:ci
open build/test-results/lcov-report/index.html

🌐 View coverage from GitHub:
Download the "coverage-report-client" artifact from this workflow run.

[ge94zec]

LGTM, thanks for implementing! I tested it on test server :)

[Cathy0123456789]

Tested on TS, works great thank you! Does it make sense to add this as well for the Research Group Detail page for admins since the Save button is at the top too?

[Cathy0123456789]

Approving, admin page will be adjusted sometime later on

[Abi107717]

Thank you, tested locally LGTM