[Meta] Merge block_field module

Problem/Motivation

This module has a lot of functionality in common with block_field.

Let's identify what's left to make it possible to merge block_field with this module.

• #3213618: Provide plugin reference builder formatter
• #3213613: Add right cache tags to the formatters
• #3213622: Add access check to formatters
• Make referenced plugins context aware
• #3214896: Add a plugin selection handler