🚧 Add stream to map

Still need to handle the codecs. But almost there.

src/Traits/HasMetadata.php

@@ -0,0 +1,21 @@
+<?php
+
+namespace Danjones\FFMpeg\Traits;
+
+trait HasMetadata
+{
+    protected array $metadata = [];
+
+    public function addMetadata(array|string $keyOrData, string $value = null): static
+    {
+        if (is_array($keyOrData)) {
+            array_walk($keyOrData, fn($v, $k) => $this->addMetadata($k, $v));
+
+            return $this;
+        }
+
+        $this->metadata[$keyOrData] = $value;
+
+        return $this;
+    }
+}