[1/2] Base: implement App circle sidebar

Change-Id: I08d2a3a7e0f8df20e801e585d4cac8547a740a3e
Base: implement Floating window

access from app circle sidebar

Change-Id: Iad00c239de7d66e8bb45205ce626d4f08417b7cd
Base: implement Floating window

access from app circle sidebar

https://gerrit.omnirom.org/#/c/6380/