Frontent dev env (#247)

* Added frontend development files/environment

* More items-categories related removals

* Improvements in pages templates (inc. static pages)

* Improvements in video player

* Added empty home page message + cta

* Updates in media, playlist and management pages

* Improvements in material icons font loading

* Replaced media & playlists links in frontend dev-env

* frontend package version update

* chnaged frontend dev url port

* static files update

* Changed default position of theme switcher

* enabled frontend docker container

frontend/packages/vjs-plugin-font-icons/custom-icons/picture-in-picture-exit.svg

@@ -0,0 +1,4 @@
+<svg xmlns="http://www.w3.org/2000/svg" width="22px" height="18px" viewBox="0 0 22 18" fill="#000000">
+  <path d="M18 4H4v10h14V4zm4 12V1.98C22 .88 21.1 0 20 0H2C.9 0 0 .88 0 1.98V16c0 1.1.9 2 2 2h18c1.1 0 2-.9 2-2zm-2 .02H2V1.97h18v14.05z" fill="#000" fill-rule="nonzero"/>
+  <path fill="none" d="M-1-3h24v24H-1z"/>
+</svg>