Created "person panel" block which displays in content area for a person

Also moved contact details view config to zencrm_entities because it is referenced as an entity reference view in a base field on Hat.

src/Plugin/Block/PersonPanel.php

@@ -0,0 +1,57 @@
+<?php
+
+namespace Drupal\zencrm\Plugin\Block;
+
+use Drupal\Core\Block\BlockBase;
+
+/**
+ * Provides a 'PersonPanel' block.
+ * If the person has no contact details it advises to create them.
+ * If they have no hats it advises to create them.
+ *
+ * @Block(
+ *  id = "person_panel",
+ *  admin_label = @Translation("Person Panel"),
+ * )
+ */
+class PersonPanel extends BlockBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  public function build() {
+    $person_id = \Drupal::routeMatch()->getParameter('person')->id();
+    $markup = "";    
+    $person = \Drupal::entityTypeManager()->getStorage('person')->load($person_id);
+
+    // If the person has no contact details, suggest they create some
+    $link_to_add = "/zencrm/contact_details/$person_id/add?destination=/zencrm/person/$person_id";
+    $contact_details = \Drupal::entityTypeManager()
+      ->getStorage('contact_details')
+      ->loadByProperties(['person' => $person_id]);
+    if (!reset($contact_details)) {
+      $markup .= "<p>This person has no contact details yet. To get started, ";
+      $markup .= "<a class='use-ajax' data-dialog-type='modal' href = $link_to_add>Add a set of contact details</a>";
+      $markup .= "</p>";
+    }
+
+    // If the person has no hats, suggest they create one, by rendering the hat creator block
+    $link_to_add = "/zencrm/hat/$person_id/add?destination=/zencrm/person/$person_id";
+    $hats = \Drupal::entityTypeManager()
+      ->getStorage('hat')
+      ->loadByProperties(['person' => $person_id]);
+    if (!reset($hats)) {
+      $markup .= "<p>This person has no hats yet. A hat is a role that the person plays in the organisation. To get started, add a hat for this person. </p>";
+      $plugin_manager = \Drupal::service('plugin.manager.block');
+      $block = $plugin_manager->createInstance('hat_creator', array());
+    }
+    $markup .= render($block->build());
+    return [
+      '#cache' => [
+         'max-age' => 0,
+       ],
+      '#markup' => "<div>$markup</div>"
+    ];
+
+  }
+}