[RAPPS] appview displaymode support (#3008)

[RAPPS] appview displaymode support (#3008)

* [RAPPS] add function to set view-mode
* [RAPPS] move toolbar and searchbar into appview
* [RAPPS] remove settings and exit button from toolbar
* [RAPPS] add code to switch between list and tile mode
* [RAPPS] add auto-arrange for listview
* [RAPPS] adjust the minimum size of AppView
* [RAPPS] now image list of listview is stored inside the class
* [RAPPS] add list mode, and old list-mode are detail mode now
* [RAPPS] add check for unimplemented view mode