initial COmmit: Add KB Antora Importer plugin files

kb-antora-importer/includes/Repository/VersionRepository.php

@@ -0,0 +1,18 @@
+<?php
+declare(strict_types=1);
+
+namespace KbAntoraImporter\Repository;
+
+final class VersionRepository
+{
+    public function ensure(string $version): int
+    {
+        $term = term_exists($version, 'kb_version');
+
+        if (! $term) {
+            $term = wp_insert_term($version, 'kb_version', ['slug' => sanitize_title($version)]);
+        }
+
+        return is_wp_error($term) ? 0 : (int) ($term['term_id'] ?? $term);
+    }
+}