fix: handle target attribute on remote form redirects

[ai-man-codes]

closes #15197

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Problem

Remote forms with target="_blank" did not open the redirect destination in a new tab. Instead, the current tab would navigate to the redirect URL, making target="_blank" completely ignored for both internal and external redirects.

Solution

Check the form element's target attribute before deciding how to navigate. If it's _blank or _new, use window.open() instead of _goto()

I have ran all the tests and there were no issues.

[changeset-bot]

🦋 Changeset detected

Latest commit: e530b52

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

This PR includes changesets to release 1 package

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@sveltejs/kit	Patch

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[svelte-docs-bot]

Preview: https://svelte-dev-git-preview-kit-15457-svelte.vercel.app/

[ai-man-codes]

@teemingc can you please review this PR ? Thank you

[teemingc]

Thanks for the PR! There are some additional edge cases we need to account for which I've highlighted in the comments. Also, there might be a way to simplify the window opening handling.

[ai-man-codes]

Hey @teemingc, thanks for the detailed review. I have updated the code and yes there was a better way of handling this, I tried to implement that and also added an additional test.

[teemingc]

Thank you!