Allow to display Bootstrap modals in side menu and user menu
Feature that refers to #5078
This PR allows to display modals in the main menu and the user menu at the top-right of the page.
Hope you will appreciate this feature :)

Thanks for this contribution.
Maybe I didn't look into the code in the right way, but I think there's something missing here. We have a menu item that opens a modal ... but where do you define the modal contents or the URL loaded dynamically via JS to render the modal contents?
@javiereguiluz The modal contents is defined in any user twig template that overrides the layout.html.twig. In other words, it is the responsibility of the user to define the modal where he wants.
**** Update *****
I added a parameter in the linkToModal function that allows to set a twig template path that defines the modal contents
@javiereguiluz Merge conflict fixed :)
@javiereguiluz If you want to merge this, merge conflict fixed (due to menu translation labels)