I cannot find this option in the new version - and the "custom css/js" option in toolset menu is not there either.
Is there a solution on how to add js to a content template without hacking around too much?
When editing templates with Blocks there is a custom CSS editor in the side panel, but support hasn't been added for a custom JS panel.
I've created a request for the developers for this to be supported because I don't see an existing ticket.
In the meantime it should be reasonably straightforward.
Such a custom JS editor would simply print your code into the markup inside script tags, and you can do the same by inserting a custom HTML block into the template, adding opening and closing script tags, the writing your custom JS between those.