Nested Layout Paragraphs modal issues

Problem/Motivation

Adding new Nested Paragraphs using the Layout Paragraphs widget don't inherit configuration defined by the Layout Paragraphs module. Notably, configuration added in the src/Utility/Dialog.php file does not apply to nested modals/dialogs.

Editing existing Nested Paragraphs seems to work fine!

Steps to reproduce

1. Enable Layout Paragraphs at 2.0.x (tested with 2.0.0-beta6).
2. Add a nested Paragraph (Paragraph that has a field with another Paragraph, both using Layout Paragraphs widget)
3. Add a new nested Paragraph
4. Notice new modal does not have "lpb-dialog" class or inherit modal width/height configuration defined in the module

Alternatively, use a multi-media-image paragraph in a layout. The media selection opens the second modal, which makes this quite easy to reproduce!

Thereby this issue: #3252978: Large modal exceeds viewport height without scrollbar = actions unreachable → which is fixed for first-level-modals still exists for nested modals.

Proposed resolution

Make "nested" modals use the proper classes/styling