Remove all remaining interfaces in the JSON API module that have only one implementation

This patch removed CurrentContextInterfaceand FieldResolverInterface interfaces

A few docblock fixes needed:

+++ b/src/Context/FieldResolver.php
@@ -50,7 +59,16 @@ class FieldResolver implements FieldResolverInterface {
+   *   The publicI field name to map to a Drupal field name.

Typo: publicI

+++ b/src/LinkManager/LinkManager.php
@@ -70,7 +92,18 @@ class LinkManager implements LinkManagerInterface {
+   * Get the full URL for a given request object.
+   *
+   * @param \Symfony\Component\HttpFoundation\Request $request
+   *   The request object.
+   * @param array $link_context
+   *   An associative array with extra data to build the links.
+   *
+   * @throws \Drupal\jsonapi\Error\SerializableHttpException
+   *   When the offset and size are invalid.
+   *
+   * @return string
+   *   The full URL.

This docblock seems to be for getRequestLink(). (was incorrect in the interface as well)

+++ b/src/Resource/EntityCollection.php
@@ -56,21 +56,33 @@ class EntityCollection implements EntityCollectionInterface {
+   *   TRUE if the collection has a next page.

no @return

+++ b/src/Normalizer/JsonApiDocumentTopLevelNormalizer.php
@@ -135,7 +135,7 @@ class JsonApiDocumentTopLevelNormalizer extends NormalizerBase implements Denorm
-   * @return \Drupal\jsonapi\Normalizer\Value\EntityNormalizerValueInterface
+   * @return \Drupal\jsonapi\Normalizer\Value\DocumentRootNormalizerValue

This looks like the wrong class

Reviewing this