Add field formatter to view which metatags are being rendered

This is useful for me. I need a view that shows all the posts/nodes and their respective meta description and titles. This is important for content authors looking at a bunch of posts. I have a view of several hundred blog posts, and we want to see their display titles, along with their authored meta titles and descriptions. This patch accomplishes this need.

It would be great to see this adopted and added to the main module.

I think we need to be careful around adding functionality that could cause confusion in the output.

Some ideas for improving it:
* Add an access check that requires the "Administer meta tags" permission, otherwise nothing is displayed.
* Extend it to add an option to output all of the entity's meta tags, not just the values stored in the field.

Let's consolidate efforts around this similar issue: ✨ Provide field formatter to output meta tags on-page, e.g. for use with Views (D9) Needs work