Parent issue #13326

With the introduction of the Scan screen, we can introduce support for redirection to Scan screen from the notifications. Previously, the app would redirect the user to a webview.

Merge instructions:

1. Make sure FluxC's PR is merged first
2. Update FluxC tag
3. Remove "Not ready for merge label

To test:
Prerequisities:

• disable Scan feature flag

1. Go to Notifications
2. Click on a "Jetpack Scan detected a possible security threat" item
3. Click on "Site's Scan Results" span
4. Notice a webview is shown

Prerequisities:

• enable Scan feature flag

1. Go to Notifications
2. Click on a "Jetpack Scan detected a possible security threat" item
3. Click on "Site's Scan Results" span
4. Notice Scan screen is shown
5. Run the test again, but make sure that you have selected a different site (SiteB) in the app than the one (SiteA) on which the threat was found -> make sure the Scan screen is shown for SiteA

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.