Styling changes for making UI-layout more manageable

[ZakarFin]

The purpose is making upcoming layout changes easier and clean up some of the dead CSS/code regarding sizing/layout.

Goals:

• Use one root element for app that is assigned at startup (or currently tries to find an element with id oskari as root)
• If there is no root element, assign required style changes to body-tag assuming fullscreen app.
• Remove most of DOM-structure and CSS from JSP/base HTML at server and move them to client side code.
• Try keeping required changes to minimum/mostly functional as is
• Remove usage of hardcoded ids for assumed elements from code (#mapdiv, #contentMap, #maptools etc). Use getters from code to get references to elements.
• Remove dead code that was used for removed functionalities to calculate sizes of elements etc.

TODO/broken things:

• Mapmodule mobile <> desktop mode change is broken (starting on either mode works, changing from mode to another doesn't)
• Exiting publisher after previewing map on non-default size doesn't reset the map size to full size
• UI during initial loading/app startup looks broken -> Maybe show a spinner instead of an empty navigation bar while starting up

Note: Current JSP/HTML changes: https://github.com/oskariorg/sample-server-extension/compare/develop...ZakarFin:styling?expand=1

Tthe geoportal_white.jsp can be used to see what the geoportal looks like without touching the HTML. It's mostly working like before. Differences are:

• size of the navigation bar is actually the one set on the HTML-style (153px instead of 170px that was enforced by frontend code without these changes).
• Scrollbar shows for the whole page instead of the navigation bar if the window is too small to show the whole nav bar.