Deprecate use of NaiveDateTime in APIs

**Is your feature request related to a problem or challenge? Please describe what you are trying to do.**

NaiveDateTime is hard to use correctly, and it is very easy to introduce subtle bugs.

https://github.com/chronotope/chrono/releases/tag/v0.4.35 deprecated a large number of methods on NaiveDateTime for this reason, we should follow their example

**Describe the solution you'd like**

I would like to alter these methods to return `DateTime`

**Describe alternatives you've considered**

**Additional context**

The issue names no files, tests, or specific methods. Start by locating APIs that return NaiveDateTime and review the referenced chrono deprecations; done means the affected APIs return DateTime and the project’s tests and build pass.

Written by the indexing model from the issue text.