Name and order the view code

Every package-level name of the view starts with view: its size limits,
the pending mark, the saved state ViewState, and the interface
ViewNodeReader. The layout of the view messages in the turn requests is
in view_layout.go, as ViewLayout. The limits chatHigh and compactionHigh
read as limits of the chat and of the compactor, but they are limits of
the two views.

The declarations of the view files follow the order of the go-code
skill. The behavior does not change.

Issue: 947bddb