Better display for document fields in list view and card view

[oplik0]

This change resolves #6522 by serializing documents to plain text for list view. Additionally, I changed the display for card view from JSON to a DocumentRenderer - while the former may be useful to a developer, I feel like many end users are not developers and might be expecting that their rich text will be at least readable.

[vercel]

This pull request is being automatically deployed with Vercel (learn more).
To see the status of your deployment, click below or on the icon next to each commit.

🔍 Inspect: https://vercel.com/keystonejs/keystone-next-docs/CtcpyxDgEdDYvNswK9SkcFAurtAx
✅ Preview: https://keystone-next-docs-git-fork-oplik0-document-f-8bcfe6-keystonejs.vercel.app

[changeset-bot]

🦋 Changeset detected

Latest commit: 887f2a1

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@keystone-next/fields-document	Minor

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[codesandbox-ci]

This pull request is automatically built and testable in CodeSandbox.

To see build info of the built libraries, click here or the icon next to each commit SHA.

[oplik0]

Hmm... I'm not sure if it was something with the commits that were rebased in this PR when 9e41771 ran, but it seems that with current code the tests should pass the integration tests: https://github.com/oplik0/keystone/actions/runs/1317933747 (made a separate branch with action changed so it'll run there).