Allow full or reduced summary

Problem/Motivation

Folow-up from #2857112: Add summary method into paragraph entity

We discuss here.
The reduced version will skip elements that have an icon, covered in the ui already.
-That is now and likely also in the future in the UI somehow. also doesn't actually seem to be in the summary despite being in the code, will check that. But again, letting code decide that is tricky, just because we *support* icons doesn't mean everyone will have time, so possibly a setting instead. But we can also add a currently empty $context or $options array and we'll add options through that in the future. then we're flexible.
-A pattern about summary could be that the (tbd) icon methods will return icon definitions with keys. Then we could pass in options to the summary with some skip key that gets the icon keys that are displayed otherwise. The summary then excludes them on creation.

Proposed resolution

A flag if it should be full or reduced.

Remaining tasks

User interface changes

API changes

Data model changes