Components: Add ThreatModal (#40197)

* Add ThreatDetailsModal component and stories

* changelog

* Fix type error

* Fix child component overflow-x styling

* Update scan package changelog

* Add util for fixerState and separate subcomponents

* Generalize component name

* Updates after renaming

* Ensure close button exists for vulns modal

* Fixes and improvements

* ThreatModal: Add user connection gate (#40204)

* Add user connection gate

* Fix stories

* ThreatModal: Add credentials gate (#40205)

* Add credentials gate

* Fix stories

* Fix credentials type

* Fix build issues, and add early returns for gates

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/11919780318

Upstream-Ref: Automattic/jetpack@c783873