add locale to user (#1363)

## Description

adds `locale` to the User object, adds support for updating User locale

## Documentation

Does this require changes to the WorkOS Docs? E.g. the [API
Reference](https://workos.com/docs/reference) or code snippets need
updates.

```
[X] Yes
```

If yes, link a related docs PR and add a docs maintainer as a reviewer.
Their approval is required.