[navSide] Hide beforeMain, afterMain, bottomSection on mobile

[shajz]

Currently, the navSide allows the use of beforeMain, afterMain and bottom sections. These are displayed when viewing the menu on mobile.

The issue can be viewed on the demo project of the ngx Lucca Sitemap :

Here, menu is closed but we can see the three sections are displayed

Here, the menu is opened, everything is a-ok :

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We talked with @GuillaumeNury about this issue, it seems adding navSide-item to the projected content works. But this is a bit hacky. We probably need a specific scss rule for these sections.