Fix: Implement missing GLPI plugin registration functions

Adds the following mandatory functions to setup.php to ensure the plugin
can be correctly registered and identified by GLPI:

- `plugin_version()`: Parses plugin.xml to provide metadata such as name,
  version, author, and compatibility to GLPI.
- `plugin_init_options()`: Returns essential plugin identifiers like
  its key and display name.
- Stub functions `plugin_check_prerequisites()`, `plugin_check_config()`,
  and `plugin_display_config()`: Added to prevent potential errors and
  serve as placeholders for future functionality.

These changes address the issue of the plugin not appearing in the GLPI
plugin installation interface.

setup.php

@@ -1,4 +1,118 @@
 <?php
+
+/**
+ * Get plugin version information
+ *
+ * @return array
+ */
+function plugin_version() {
+    $xml = simplexml_load_file(__DIR__ . '/plugin.xml');
+
+    if ($xml === false) {
+        // Handle error: plugin.xml not found or unreadable
+        return []; // Or throw an exception
+    }
+
+    $authors = [];
+    if (isset($xml->authors) && isset($xml->authors->author)) {
+        foreach ($xml->authors->author as $author) {
+            $authors[] = (string)$author->name . (isset($author->email) ? ' &lt;' . (string)$author->email . '&gt;' : '');
+        }
+    }
+
+    $versions = [];
+    if (isset($xml->versions) && isset($xml->versions->version)) {
+        foreach ($xml->versions->version as $version) {
+            $versions[] = [
+                'num'            => (string)$version->num,
+                'minGlpiVersion' => (string)$version->compatibility, // GLPI expects minGlpiVersion
+            ];
+        }
+    }
+
+    $langs = [];
+    if (isset($xml->langs) && isset($xml->langs->lang)) {
+        foreach ($xml->langs->lang as $lang) {
+            $langs[] = (string)$lang;
+        }
+    }
+
+    $tags = [];
+    if (isset($xml->tags)) {
+        foreach ($xml->tags->children() as $lang_code => $tag_list) {
+            $current_tags = [];
+            foreach ($tag_list->tag as $tag) {
+                $current_tags[] = (string)$tag;
+            }
+            $tags[$lang_code] = $current_tags;
+        }
+    }
+
+
+    return [
+        'name'              => (string)$xml->name,
+        'key'               => (string)$xml->key,
+        'state'             => (string)$xml->state,
+        'logo'              => (string)$xml->logo,
+        'shortdesc'         => (string)$xml->description_short, // GLPI expects shortdesc
+        'longdesc'          => (string)$xml->description_long,  // GLPI expects longdesc
+        'homepage'          => (string)$xml->homepage,
+        'download'          => (string)$xml->download,
+        'issues_tracker'    => (string)$xml->issues,           // GLPI expects issues_tracker
+        'readme'            => (string)$xml->readme,
+        'authors'           => $authors,
+        'versions'          => $versions,
+        'langs'             => $langs,
+        'license'           => (string)$xml->license,
+        'tags'              => $tags,
+        'minGlpiVersion'    => !empty($versions) ? $versions[count($versions)-1]['minGlpiVersion'] : '' // Default to last version's compatibility
+    ];
+}
+
+/**
+ * Initialize plugin options
+ *
+ * @return array
+ */
+function plugin_init_options() {
+    return [
+        'name'    => __('SOC Case Management', 'soc'),
+        'key'     => 'soc',
+        'tooltip' => __('SOC Case Management integration plugin for security teams.', 'soc'),
+    ];
+}
+
+/**
+ * Check plugin prerequisites.
+ *
+ * @return boolean
+ */
+function plugin_check_prerequisites() {
+    // For now, always return true
+    return true;
+}
+
+/**
+ * Check plugin configuration.
+ *
+ * @param boolean $verbose Enable verbose mode (default false)
+ *
+ * @return boolean
+ */
+function plugin_check_config($verbose = false) {
+    // For now, always return true
+    return true;
+}
+
+/**
+ * Display plugin configuration page.
+ *
+ * @return void
+ */
+function plugin_display_config() {
+    // Currently does nothing
+}
+
 /**
  * Init the hooks of the plugin
  *