Add global headers to the client

[ytkimirti]

Example usecase:

import { Client } from "@upstash/qstash"

const client = new Client({
  token: "token",
  headers: {
    "x-vercel-protection-bypass": process.env.VERCEL_AUTOMATION_BYPASS_SECRET,
  }
})

[linear]

DX-1451 Add global headers capability to QStash and Workflow clients

[CahidArda]

can we add more tests? Here is what I would like to see:

• create a client with headers: {"undefined-header": undefined, "TEST-HEADER": "override-value", "test-header": "override-value-ignored", "TEST-HEADER-2": "override-value-2"}. We should see that the headers are case insensitive, and batch shouldn't have two headers for test-header for instance.
• for every method (publishJSON, batchJSON, enqueue, schedule): call the methods with headers like {"stays-the-same": "same", "test-header": "overridden-value"} and check the values of every header.

[fahreddinozcan]

Suggested change

	private wrapWithGlobalHeaders(headers: Headers) {
	const finalHeaders = new Headers(this.headers);
	// eslint-disable-next-line unicorn/no-array-for-each
	headers.forEach((value, key) => {
	finalHeaders.set(key, value);
	});
	return finalHeaders;
	}
	private wrapWithGlobalHeaders(headers: Headers) {
	const finalHeaders = new Headers(this.headers);
	// eslint-disable-next-line unicorn/no-array-for-each
	headers.forEach((key, value) => {
	finalHeaders.set(key, value);
	});
	return finalHeaders;
	}

Why do we even have this function? Are we trying to reverse the headers' key value? The user should already give them as

    const clientWithHeaders = new Client({
      token: process.env.QSTASH_TOKEN!,
      headers: {
        "test-header": "value",
        "test-header-2": "value-2",
      },
    });

[ytkimirti]

It is reversed in the api for no reason. It seemed weird to me too

[CahidArda]

how about schedules & enqueue?