Manage /sites: add options to create custom filters

[liviopv]

What

The Site Management screen (/sites) should have more options to filter different sites, so developers and agencies can more easily navigate through multiple sites without needing to search.

Why

If one has a lot of sites associated with one account (like a12s and Agencies might have), it's hard to find the site unless you know what you're searching for, which is not always the case.

We should add more filter options and allow users to create custom views based on those filters (examples: "sites I'm an editor in tagged with prime clients", "sites tagged asprime clients with plugin-installed:yoast and active:true)

How

Filters:

• User role: owner, admin, editor, etc
• Star/Favorites
• Custom taxonomy just for /sites, like a simple tag system
• Plugin & Plugin status
• Theme & Theme status
• Filter by PHP version
• Active subscriptions

[dsas]

Related idea: https://github.com/Automattic/dotcom-forge/issues/4566