Move searchbar of brisk menu inside applications box

[Frieder_Saugschmerle]

The code from comment /* Create search entry - but not GtkSearchEntry to avoid rounding in themes / upto / Content Layout*/ needs to be moved inside src/frontend/classic.c. But on which position? So that the search bar is inside the application container. Dont ask why it uses unecessary screen space like it is now.

Made brisk switch the category and applications box container so that its more meaningful this way.

here is shown how to get rid of favorites default option or this thing even completly b.t.w: Make favorites appear first by gabrc52 · Pull Request #5 · getsolus/brisk-menu · GitHub

[Frieder_Saugschmerle]

I did now manage to remove the searchbar and favoritesbox. Better would be to move the searchbar but like this its already ten times better than it was.

The application-/content ? box would beed to be packed inside a vbox with the search menu.
Looking at the souece code will also improve css styling possibilities. As it is themeable.