Add paragraph settings summary pointing out the changed settings (non-default values)

Paragraph settings are quite complex and when editing existing paragrahs, you often have to compare which values changed (!= default). Like with field settings or block filters, it would help a lot to point out the changed (non-default) values without having to look at all settings tabs.

Additionally, it might be helpful to also mark each changed field individually, which shouldn't be too hard by for example adding a class.

@thomas.frobieter what do you think about the ideas?

Proposed solution:

- [ ] Mark fields with non default values with a general css class (to be defined by @thomas.frobieter)
- [ ] Display default value below the field, as "-" is not always the default
- [ ] Output summary of changed values at high level, e.g. the fieldset description, if possible. (esp. 1.x)
- [ ] Output summary in preview through twig variables (4.x)

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For 4.x:

1. Determine the modified values (!= default value)
2. Pass those values to the paragraph.html.twig
3. Create a drowl_paragraphs.admin_settings_preview library to deliver the required CSS & JS
4. If possible, link the preview values to the settings form (+ open the right fieldset + tab)
5. Older Versions (pre-Layout-Paragraphs): Maybe we should print out the modified settings in the paragraph edit form too?

We already have something similar for Container-Paragraphs in the Paragraphs preview (Layout Paragraphs):

So we should standardize this and reuse it for the rest of the values, but we should differ between values which show up directly (like the background-image preview here) and an expandable container holding other modified values.

In case of the background settings, the values are printed out right inside the paragraphs.html.twig (only for the preview view mode used in Layout Paragraphs).

Idea: