Fix content_tag_for with array :class option

It would embed array as string instead of joining it like content_tag does:

```ruby
>> helper.content_tag(:td, class: ["foo", "bar"]){}
=> "<td class=\"foo bar\"></td>"
>> helper.content_tag_for(:td, item, class: ["foo", "bar"]){}
=> "<td class=\"item [&quot;foo&quot;, &quot;bar&quot;]\" id=\"item_1\"></td>"
=> "<td class=\"item foo bar\" id=\"item_1\"></td>"
```

Issue #9047