feat(core): Add cron monitor wrapper helper

[AbhiPrasad]

In #8039 we added functionality for Sentry.captureCheckIn as part of Sentry's cron monitoring product.

This PR adds Sentry.withMonitor, a wrapping function similar to Sentry.startSpan that wraps a callback with a cron monitor. Under the hood it uses Sentry.captureCheckIn, but having this as a callback means that users don't have to think about passing checkInId around.

import * as Sentry from '@sentry/node';

// with monitor will send checkin when callback is started/finished
// works with async and sync callbacks.
const result = Sentry.withMonitor(
  'dailyEmail',
  () => {
    // withCheckIn return value is same return value here
    return sendEmail();
  },
  {
    schedule: {
      type: 'crontab',
      value: '0 * * * *',
    },
    // 🇨🇦🫡
    timezone: 'Canada/Eastern',
  },
);

[lforst]

Some sort of test would be cool!

[AbhiPrasad]

Based on some feedback in slack I renamed this to withMonitor. This all matches what the Python SDK does with a wrapping API.

I will add some tests!