Restructure around `products`

[patrickhulce]

We've introduced the concept of products to third-party-web that can be subsets of an entity's resources.

Guidelines:

• An entity is a thing with distinct independence that offers some web functionality. It isn't necessarily a company, but at least a large group. Create an entity when that group has clear ownership over some set of domains, a distinct logo/brand identity, or obvious distinction from their parent company. Examples: Google Maps, ZenDesk, Instagram
• A product is some subset of functionality offered by an entity. Create a product when an entity does multiple different things that need to be further segmented. Examples: Google Maps Embedded API, Zendesk Zopim, Instagram Ads (for conversion tracking)

We want to add this guidance to our README and restructure a few of the entities that make more sense as products (mostly the major players that are thrown together, a few popular libraries, etc)

[patrickhulce]

Specifically for Google Ads we can use some of google ads own classification mechanisms: https://github.com/googleads/publisher-ads-lighthouse-plugin/blob/6ece2c93a1b1de57a29ba2428279ca6f70db2fc3/lighthouse-plugin-publisher-ads/utils/resource-classification.js#L381-L389