window: Rename from window-base
Also, always use window for detached notes too. If the main window is closed, any one of the detached window should be set as main window, which means that all note windows (regardless of whether they are detached or not) should be a main window.
/cc @igaldino
There are a few issues with notes currently (which seems to have happened after the new design landed). These issues shall be fixed in different MR(s)