Simplifies document routing in the following ways:
- Removes duplicative code blocks that made it easy to make changes to
collections but not globals
- Consolidates `CustomView`, `DefaultView`, and `ErrorView` into just
`View`
- Removes unnecessary `overrideDocPermissions` arg
- Standardizes the 404 logic when the doc lacks read access
- Fixes styling issue where `UnauthorizedView` is rendered without
margins, e.g. when you lack permission to read versions but navigate to
`/versions`
b556fe3daf