Define content name before saving a new H5P content

While working on MDL-68937, it was raised that synchronising the H5P title might fix some issues but will create new ones (because it was not always the expected behaviour).

The issue was analysed with the UX team and Rafael Lechugo prepared a prototype for fixing the scenario causing this title confusion: the first time an H5P content is saved, the content name is synchronised to the H5P title. The prototype is about adding a modal for letting users to define the content name before they save a H5P content by first time: https://projects.invisionapp.com/share/J7Z11HRPKX3#/screens/434055843