Customize modal for creating embedded content

Problem/Motivation

The popup for the modal seems very small and often leads to horizontal scrolling.

Steps to reproduce

Enable the example module and added a styles_list plugin

Proposed resolution

Either make it configurable to be large or make it large (maybe half size of screen?)

Remaining tasks

Agree on approach
Implement
Test
Commit

User interface changes

NA

API changes

NA

Data model changes

NA