Project: #15190

This PR adds:

• Adds logic to start / stop auto refreshing the state every 5 seconds when a scan is in progress.
• Adds pull to refresh on the scan view
• Changes the coordinator to a lazy var
• Adds a relationship between the JetpackScanStatusViewModel and the JetpackScanCoordinator
• Placeholders for the fix / contact support actions
• Ability to start a scan

Screenshots

To test:

1. Launch the app
2. Tap on My Sites
3. Tap on a Jetpack site with Scan enabled
4. Tap on Scan
5. Tap on the 'Start Scan' button
6. 👁️ The state immediately changes to "preparing"
7. After 5 seconds the progress should update
8. Pull down to manually trigger a refresh
9. Wait for the scan to finish
10. The state should return to idle (okay 🟢 or threats detected 🔴 )
11. Open the site on wordpress.com
12. Initiate a scan
13. In WPiOS pull to refresh
14. 👁️ You should see the state change, and the view start polling every 5 seconds again
15. After the scan finishes tap back
16. Go back to the wordpress.com and trigger another scan
17. In WPiOS tap on the site
18. 👁️ You should see the scanning state, and it refreshing every 5 seconds

PR submission checklist:

• I have considered adding unit tests where possible.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.