This is terminology clean-up.

We agreed to use "container".
Specifically, if it is running without Mojo connection to speed up the boot, we call it "mini container".
The one with Mojo connection is called "full container".

We'd rename:
ArcSession/ArcSessionImpl to ArcContainer/ArcContainerImpl.
ArcInstanceMode to ArcContainerMode, ditto for its values.
Also, many comments using "instance" should be "s/Instance/Container/"'ed, in components/arc, c/b/c/arc, ui/arc, and c/b/ui/app_list/arc.

Note that, we'd keep Instance for mojo class names.