secure_backup_required not enforced on "Phase.Passphrase" step and with manual URLs change/page reloads

[yasinishyn]

Steps to reproduce

I found 3 ways to skip the key backup:

#### 1 Set a Security Phrase:

1. Setup the server with the secure_backup_required .well-known setting;
2. Login into element_web UI (or create a new account);
3. (for existing accounts) On the Verify this device step click on Reset All and confirm the reset;
4. On the Set up Secure Backup step select the Enter a Security Phrase option;
5. Click on x or click outside the modal, or click on cancel;

#### 2 Set a Security Phrase -> Confirm login:

1. Execute steps 1 to 4 from the above;
2. Create and confirm security Phrase on the Set a Security Phrase and Confirm Security Phrase modal pages;
3. Download or copy the backup on the Save your Security Key page;
4. Click on x or click outside the modal, or click on cancel on the Auth confirmation page that appears after;

#### 3 Manual URL change or page refresh:

1. Execute steps 1 to 3 from the 1 Set a Security Phrase;
2. manually change the URL to any existing room URLs or just refresh the page.

*#### Related bug
You can't close the Set up Secure Backup window if the flow was started from the settings page even if the current user has a valid e2e setup.

Related PR: matrix-org/matrix-react-sdk#5130 (comment)

Please find attached screen recordings showing the issue

Screen.Recording.2022-11-21.at.20.51.44.mov

Screen.Recording.2022-11-21.at.20.57.59.mov

Outcome

#### What did you expect?
Sending messages, reading messages, etc... should not be possible unless the e2e key is created and the backup is saved.

#### What happened instead?
The cancel button and x is only hidden for the Set up Secure Backup and Save your Security Key modal windows and the key backup can be easily skipped in the Set a Security Phrase flow or manual URL update or/and page refresh.

Operating system

macOS

Browser information

Version 107.0.5304.110 (Official Build) (arm64)

URL for webapp

#/home, #/login, #/

Application version

1.11.14

Homeserver

matrix.org

Will you send logs?

No

[yasinishyn]

Adding an example PR go give an idea of how this might be fixed - matrix-org/matrix-react-sdk#9729