LG-12609 piv interstitial method

[mdiarra3]

🎫 Ticket

Link to the relevant ticket:
LG-12609

🛠 Summary of changes

This adds an interstiatial page that takes into account when users use a .gov or .mil account and prompts them to add a PIV card if it comes from PIV/CAC cards.

📜 Testing Plan

Provide a checklist of steps to confirm the changes.

• Test Account Creation flow

1. Create account with email as .gov
2. User is prompted to add PIV Cac as MFA before selecting MFA
3. User can Add Piv and then directed to Second MFA reminder
4. User can skip and be redirected to MFA selection screen

• Account Sign in flow

1. User with a .gov account (Can do this by having a regular account and then adding a .gov account to their email).
2. User is prompted to enter existing MFA
3. AFter successful full sign in they are prompted to set up PIV Cac as authentication method
4. User can skip and go forward, or can add a PIV and be redirected to final sight.

New User interstitial

Existing User interstitial

[mdiarra3]

Needs #10315 to be merged and rebased before we can merge this

[aduth]

LGTM 👍 Few minor comments, but tested well for me locally