Ignore packages with the same version for cudf.
Improve local <-> remote universe handling.

- Unify pkg_need_upgrade calls.
- Do not return confusing error if we don't want to update already installed packages.
- Fix update and reduce its universe size by avoiding unnecessary checks.
Improve events output.

- Improve output of `already installed` event.
- Add the number of conflicting packages to `integrity check` event.