LG-8896: Fix heading order for personal key reactivation

[aduth]

🎫 Ticket

LG-8896

🛠 Summary of changes

This pull request fixes a number of accessibility and other visual issues on the personal key reactivation screen:

1. Ensure that headings advance in order
2. Use standard submit button (big, wide)
3. Fix incorrect paddings and margins
4. Simplify stylesheets

📜 Testing Plan

1. Create an identity-verified account
2. Reset your password ("Forgot your password?" from the Sign In screen)
3. After resetting password, sign in
4. Click "Reactivate your profile" from account dashboard
5. Click "Yes, I have my personal key" button

👀 Screenshots

Before	After