Move metatag configuration into the individual modules rather than `social_metatag`

Problem/Motivation

We currently have the social_metatag module which contains metatag configuration for a lot of distribution features. However, this makes it easy to forget to update this for new features and also creates a silent dependency of the metatag module on all of our features (which is not actually set in the .info.yml module).

Steps to reproduce

Proposed resolution

We can add metatag and metatag_open_graph to our social.installer_options_list.yml file so that they can be installed as optional features that are enabled by default.

We can split the current config/modify file into a file per feature so that we can co-locate the metatag configuration within the features itself rather than requiring a centralized module.

These changes make it so we can almost remove the social_metatag entirely except some more work needed for social_metatag_metatag_route_entity.

Remaining tasks

User interface changes

API changes

Data model changes