Rename and re-organise custom modules

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

web/modules/custom/opd_talks/opd_talks.install

@@ -1,17 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-use Drupal\opd_talks\Repository\TalkRepository;
-
-/**
- * Set talk type for all existing talks.
- */
-function opd_talks_update_8001(): void {
-  $talkRepository = \Drupal::service(TalkRepository::class);
-
-  foreach ($talkRepository->getAll() as $talk) {
-    $talk->set('field_type', 'talk');
-    $talk->save();
-  }
-}