Jetpack SEO: add enhancer filter and draft (#42310)

* add a very rought first component for the SEO enhancer

* add filter and beta feature for SEO enhancer

* render the first draft for SeoEnhancer when filter is enabled and with BETA blocks

* changelog

* leave help text alone

* tidy up on the extensions file

Committed via a GitHub action: https://github.com/Automattic/jetpack/actions/runs/13768045613

Upstream-Ref: Automattic/jetpack@400b5db

Author: robertsreberski