Add ModMissingProblem and ModMissingSolution

src/Analysis/ProjectZomboid/ModMissingSolution.php

@@ -0,0 +1,24 @@
+<?php
+
+namespace IndifferentKetchup\Codex\Analysis\ProjectZomboid;
+
+use IndifferentKetchup\Codex\Analysis\Solution;
+
+class ModMissingSolution extends Solution
+{
+    private string $modName = '';
+
+    public function setModName(string $modName): static
+    {
+        $this->modName = $modName;
+        return $this;
+    }
+
+    public function getMessage(): string
+    {
+        return sprintf(
+            'Subscribe to mod "%s" or remove its ID from the Mods= line in serverconfig.ini.',
+            $this->modName
+        );
+    }
+}