Release notes for 0.98.0 (#1541)

* Release notes for `0.98.0`

Please add your new features and breaking changes to the release notes
by opening PRs against the `release-notes-0.98.0` branch.

## TODO
- [ ] look at interesting contributions
- [ ] write all the sections
- [ ] order the sections by interest
- [ ] add the breaking changes
- [ ] detail the breaking changes
- [ ] add the full changelog
- [ ] complete all the `TODO`s inside the release note
- [ ] ... (PRs that need to land before the release, e.g. [deprecations](https://github.com/nushell/nushell/labels/deprecation) or [removals](https://github.com/nushell/nushell/pulls?q=is%3Apr+is%3Aopen+label%3Aremoval-after-deprecation))

* Start 0.98.0 release notes (#1550)

* Edit 0.98.0 release notes (#1551)

* finish release notes

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Co-authored-by: Devyn Cairns <[email protected]>