Rename and re-organise custom modules

- Rename `opd_talks` to `opdavies_talks`
- Rename `custom` to `opdavies_blog`

web/modules/custom/custom/src/Entity/Node/Post.php

@@ -1,47 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Drupal\custom\Entity\Node;
-
-use Drupal\discoverable_entity_bundle_classes\ContentEntityBundleInterface;
-use Drupal\node\Entity\Node;
-
-/**
- * Defines an blog post node class.
- *
- * @ContentEntityBundleClass(
- *   label = @Translation("Blog post"),
- *   entity_type = "node",
- *   bundle = "post"
- * );
- */
-class Post extends Node implements ContentEntityBundleInterface {
-
-  public function getExternalLink(): ?array {
-    return ($link = $this->get('field_external_link')->get(0))
-      ? $link->getValue()
-      : NULL;
-  }
-
-  public function hasBeenSentToSocialMedia(): bool {
-    return (bool) $this->get('field_sent_to_social_media')->getString();
-  }
-
-  public function hasTweet(): bool {
-    return (bool) $this->get('field_has_tweet')->getString();
-  }
-
-  public function isExternalPost(): bool {
-    return (bool) $this->getExternalLink();
-  }
-
-  public function toTweet(): string {
-    // TODO: Add tags.
-
-    $parts = [$this->label(), $this->url('canonical', ['absolute' => TRUE])];
-
-    return implode(PHP_EOL . PHP_EOL, $parts);
-  }
-
-}