Place style options inside details element

Problem/Motivation

The options list can get a bit long if a good number of styles is made available.

Steps to reproduce

Proposed resolution

The editor_advanced_link → module places its additional options inside a details element, thus hiding them inside of an accordion. This makes the default dialog appear much smaller and tidier. Perhaps something similar could be done for the list of available styles?

Remaining tasks

User interface changes

API changes

Data model changes