We shouldn't be hardcoding that the CSS file is located under `/node_modules/oae-core/widgetid/css/widgetid.css`. This will give an unnecessary error for widgets without CSS, it will not pick up on potential additional widget CSS files and is not going to work for custom institutional widgets (e.g. Renuda has an oae-renuda directory next to oae-core with their custom widgets).

Instead, we should be loading the widget HTML files and process them to extract the js and css URLs, and then load these. The URL should be constructed with this in mind and shouldn't hardcode `oae-core`

Note that we can use batch requests when we need to retrieve multiple files.