Split default views into separate files

See #460248: Split default views into separate files for similar background and motivation for a similar change I did a while ago to project_issue (which also provides a lot of default views). As we make more heavy use of views (e.g. with an eye towards #582986: Make views a required dependency and ditch non-views code) I'd like to keep each default view in its own file to make them a little easier to work with.