Add paragraphs summary formatter

The summary is an admin UI output, here intentionally for a super compact output inside an administrative table.

The teaser output is typically a frontend output.
IMHO we should not use the term "teaser" for an admin UI view mode.

1. +++ b/src/Plugin/Field/FieldFormatter/ParagraphsFormatter.php
   @@ -0,0 +1,54 @@
   +class ParagraphsFormatter extends FormatterBase {
   

   ParagraphsFormatter is to generic IMHO. We should name this something like ParagraphsSummaryFormatter

2. +++ b/src/Plugin/Field/FieldFormatter/ParagraphsFormatter.php
   @@ -0,0 +1,54 @@
   +    $paragraph_type = \Drupal::entityTypeManager()->getDefinition($target_type);
   

   Inject

Direction is in my opinion good. But we need to add tests.

Old issue with an interesting link in #11: #2433933: Paragraph summary formatter

We have a lot of room for improvement in the summary area. But we could keep it simple here, so that other issues can have something to work on and we can improve it later.

+++ b/src/Plugin/Field/FieldFormatter/ParagraphsSummaryFormatter.php
@@ -0,0 +1,54 @@
+      if ($paragraph = Paragraph::load($item->getValue()['target_id'])) {

I think loading of additional information should be done in prepareView. See \Drupal\Core\Field\Plugin\Field\FieldFormatter\EntityReferenceFormatterBase::prepareView for example.

Also I see that in EntityRefferenceFormatterBase::view core tries add acces result cacheability information. Not sure if we need something similar here in the light of behavior lockable plugin. More opinions regarding that woud be wellcome.

lockable is edit, that doesn't apply here but yes, we need to respect entity view access, which

But yes, that code is very strange, just do $item->entity. And actually, in that method, the correct thing to do is the same as all other formatters, that is foreach ($this->getEntitiesToView($items, $langcode) as $delta => $entity) {

This is blocking progress for the library in collection. Plz link.

I don't see why we need to override prepareView(), isn't that the same as the parent?

Committed, thanks.