Parent: #13326

This PR builds threat item state with header + sub header based on different threat types and click listener that will take it to the threat details screen later on.

To test

Prerequisite: Make sure both Scan feature flag and MySiteImprovements flag are set to on in the App settings.

1. Select a site with scan capability on the My Site tab
2. Notice that scan menu is displayed
3. Click scan menu item
4. Notice that threat items are displayed with header and sub header based on threat types as described in the below table:
   (Tests included in ThreatItemBuilderTest)

References: Calypso's header & sub header( 1, 2)

Note

1. Ignore all styling
2. Not too much detailing is done for the messages e.g. customising FileThreatModel's SubHeader based on threat status (current/fixed/ignored)

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.