[build-utils][cli][client][node][next][static-config]: forward crons from vercel.json to config.json (#9454)

This PR changes the way cron jobs are being created in the build output
API. This is my first time contributing here. If you see something
unusual, let me know.

✅ Good for review

Our goal is to:
- Allow creating cron jobs via the `crons` property of `vercel.json` for
end users
- Allow framework authors to create cron jobs on Vercel via the `crons`
property of the Build Output API configuration

---

As you can see, we removed the previous implementation where cron jobs
could be configured at the function code level (export const cron = ""),
on top of vercel.json `functions` property. Here's why:

- All frameworks would have to implement the configure at the function
code level
- Not all frameworks can easily map a path to a specific function
(example: SvelteKit) and would have to bail on bundling functions inside
the same lambda
- Configuring a path + scheduler provides a better mapping of what cron
jobs are as of today: API routes on a schedule and not functions on a
schedule
- Dynamic routes Cron Jobs will be supported:
/api/crons/sync-slack-team/230
- Query parameters will be supported support:
/api/crons/sync-slack-team/230?secret=32k13l2k13lk21 (= securing cron
jobs v0)
- 100% frameworks compatibility from day one

Next.js and other frameworks may choose to implement their own cron jobs
feature that will then need to be configured through the `crons`
property of `config.json` (build output API).

cc @timneutkens @Rich-Harris 

Internal thread:
https://vercel.slack.com/archives/C04DWF5HB6K/p1676366892714349

packages/cli/test/unit/commands/build/index.test.ts

@@ -1104,32 +1104,20 @@ describe('build', () => {
 
   it('should include crons property in build output', async () => {
     const cwd = fixture('with-cron');
-    const output = join(cwd, '.vercel', 'output', 'functions', 'api');
+    const output = join(cwd, '.vercel', 'output');
 
     try {
       process.chdir(cwd);
       const exitCode = await build(client);
       expect(exitCode).toBe(0);
 
-      const edge = await fs.readJSON(
-        join(output, 'edge.func', '.vc-config.json')
-      );
-      expect(edge).toHaveProperty('cron', '* * * * *');
-
-      const serverless = await fs.readJSON(
-        join(output, 'serverless.func', '.vc-config.json')
-      );
-      expect(serverless).toHaveProperty('cron', '* * * * *');
-
-      const overwriteServerless = await fs.readJSON(
-        join(output, 'overwrite', 'serverless.func', '.vc-config.json')
-      );
-      expect(overwriteServerless).toHaveProperty('cron', '0 10-20 * * *');
-
-      const overwriteEdge = await fs.readJSON(
-        join(output, 'overwrite', 'edge.func', '.vc-config.json')
-      );
-      expect(overwriteEdge).toHaveProperty('cron', '10 * * * *');
+      const config = await fs.readJSON(join(output, 'config.json'));
+      expect(config).toHaveProperty('crons', [
+        {
+          path: '/api/cron-job',
+          schedule: '0 0 * * *',
+        },
+      ]);
     } finally {
       process.chdir(originalCwd);
       delete process.env.__VERCEL_BUILD_RUNNING;