Upgrade to React 18

[johnnyomair]

Description

Upgrade React to v18. Followed the official migration guide on how to upgrade.

Note: This upgrades Docusaurus as well. After spending quite some time trying to fix issues between React 17 and React 18 types, I've decided that it's easier to upgrade Docusaurus in this PR. Sorry for the many changes 😬

Acceptance criteria

• I have verified if my change requires an example
• I have verified if my change requires a changeset
• I have verified if my change requires screenshots/screencasts

Open TODOs/questions

• Should we drop support for React 17?
• Do we need an upgrade script?
• Do we need a section in the migration guide?

Further information

• Task: https://vivid-planet.atlassian.net/browse/COM-1134
• Upgrade script: Add script to update React dependencies comet-upgrade#56

[johnnyomair]

I tried to fix the type errors by only adapting types, not changing behavior. So in theory this should still support React 17. Should we remove support for React 17 anyway?

[thomasdax98]

Should we drop support for React 17?

I'm fine either way. We recommend upgrading to React 18. So I see no real benefit in keeping the support for 17. But since the changes seem to be minimal, we can also keep it.

Do we need an upgrade script?

I'd say: No. Though we could create an upgrade script that executes the React codemods

Do we need a section in the migration guide?

Yes. At least a reference to the React migration guide

[johnnyomair]

I'm fine either way. We recommend upgrading to React 18. So I see no real benefit in keeping the support for 17. But since the changes seem to be minimal, we can also keep it.

I'd say let's keep it. Maybe a project needs to upgrade to Comet 8 urgently. The upgrade to React 18 can be performed later (like we did for App Router).

I'm fine either way. We recommend upgrading to React 18. So I see no real benefit in keeping the support for 17. But since the changes seem to be minimal, we can also keep it.

These codemods aren't from the React itself and not safe in every scenario. IMO devs should explicitly decide to run them. I've mentioned them in the migration guide though.