When you search for a file (e.g. "hello world") the window title of Dolphin will now change to "Searching hello world" instead of "baloosearch - /". This commit includes creating a helper function currentSearchText() in dolphinviewcontainer.cpp which then gets called from dolphinmainwindow.cpp.
This fixes [BUG: 321575](https://bugs.kde.org/show_bug.cgi?id=321575)