fix(http) dont drop numeric headers

[cirospaciari]

What does this PR do?

Fix: #17764
Match node.js behavior for numbers

• Documentation or TypeScript types (it's okay to leave the rest blank in this case)
• Code changes

How did you verify your code works?

Test

[robobun]

^{Updated 12:05 AM PT - Feb 28th, 2025}

✅ @Jarred-Sumner, your commit 35a87044a7c3616fa684362a7277a05de2148c17 passed in Build #12482! 🎉

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🧪   try this PR locally:

bunx bun-pr 17769

PR Overview

This PR fixes #17764 by ensuring numeric header values are not dropped and are handled as strings, matching Node.js behavior.

• Adds tests in node-http.test.ts to verify that both server and client correctly handle numeric header values.
• Updates header manipulation methods in http.ts (for OutgoingMessage and ServerResponse) to convert numeric header values to strings before setting or appending them.

Reviewed Changes

File	Description
test/js/node/http/node-http.test.ts	Introduced tests verifying numeric header handling
src/js/node/http.ts	Modified header methods to stringify numeric values

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.