AK: Add ByteBuffer::append(ReadonlyBytes)

Author: https://github.com/mattco98
Commit: https://github.com/SerenityOS/serenity/commit/ffda24373ab
Pull-request: https://github.com/SerenityOS/serenity/pull/7675
Reviewed-by: https://github.com/FireFox317
Reviewed-by: https://github.com/alimpfard

AK/ByteBuffer.h

@@ -161,6 +161,11 @@ public:
         ensure_capacity_slowpath(new_capacity);
     }
 
+    void append(ReadonlyBytes const& bytes)
+    {
+        append(bytes.data(), bytes.size());
+    }
+
     void append(void const* data, size_t data_size)
     {
         if (data_size == 0)