Surface thrown response headers to ancestor boundaries

[brophdawg11]

We have a gap in the API currently where you cannot access headers from child-route-thrown-responses because we only run headers() from "renderable" matches (which means root down to the boundary). So if you throw new Response() from /parent/child and catch it in /parent - you have no way to send any child headers back from the /parent headers() function.

This PR adds a new errorHeaders parameter to headers() that holds the headers from any thrown Response triggering the error boundary.

If the route that throws the response is also the boundary route, then errorHeaders will be the same as what's already passed as loaderHeaders/actionHeaders.

We also only expose the errorHeaders to the leaf renderable match headers() function to avoid duplicating the header value through parentHeaders.

Closes #5356

[changeset-bot]

🦋 Changeset detected

Latest commit: a2725e3

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

This PR includes changesets to release 18 packages

Name	Type
@remix-run/server-runtime	Minor
@remix-run/cloudflare	Minor
@remix-run/deno	Minor
@remix-run/dev	Minor
@remix-run/node	Minor
@remix-run/react	Minor
@remix-run/cloudflare-pages	Minor
@remix-run/cloudflare-workers	Minor
create-remix	Minor
@remix-run/css-bundle	Minor
@remix-run/architect	Minor
@remix-run/express	Minor
@remix-run/netlify	Minor
@remix-run/serve	Minor
@remix-run/testing	Minor
@remix-run/vercel	Minor
remix	Minor
@remix-run/eslint-config	Minor

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[markdalgleish]

This API makes sense to me 👍

[github-actions]

🤖 Hello there,

We just published version v0.0.0-nightly-3e093e5-20230520 which includes this pull request. If you'd like to take it for a test run please try it out and let us know what you think!

Thanks!