The TLP library has very low unit-test coverage. It is unfortunate since it is used in a majority of pages in Tuleap and is included in every BurningParrot page ever.
We should unit-test it, at the very least to make sure it is stable.

As it is (very) painful to unit-test something after it has been written (in this case 4 years later), it should be done gradually.

This request focuses on some of the most heavily used components: modals, dropdowns, popovers, fetch-wrapper.

"filter-inline-table" is left out because it is the biggest "component", relies a lot on the DOM (which makes it painful to test) and has not been used very much lately. Since using Vue.js, all filtering is done through Vue rather than this module. As I don't want to drag this request forever, I prefer to split it in smaller parts. "Filter-inline-table" will have its own request.