Generalise keyboard shortcuts, add Cmd+J to AI Chat

[zenoachtig]

• Add a new generic KeyboardShortcut component
• Use it in Search and AIChat
• Add hotkey for Cmd/Ctrl+J to open the Assistant and to refocus the chat input (if unfocused).

[changeset-bot]

🦋 Changeset detected

Latest commit: 630f9dd

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

This PR includes changesets to release 1 package

Name	Type
gitbook	Patch

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[github-actions]

Summary of the deployments:

Version	URL	Status
Vercel	https://gitbook-v2-oacg1ovji-gitbook.vercel.app	✅
Cloudflare	https://8c64b07a-gitbook-open-v2-preview.gitbook.workers.dev	✅

Test content

Site	2v	2c
GitBook	https://gitbook-v2-oacg1ovji-gitbook.vercel.app/url/gitbook.com/docs	https://8c64b07a-gitbook-open-v2-preview.gitbook.workers.dev/url/gitbook.com/docs
E2E	https://gitbook-v2-oacg1ovji-gitbook.vercel.app/url/gitbook.gitbook.io/test-gitbook-open	https://8c64b07a-gitbook-open-v2-preview.gitbook.workers.dev/url/gitbook.gitbook.io/test-gitbook-open

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[nolannbiron]

@zenoachtig some small things but looks good to me otherwise