Implement a scheduling library

[jniles]

There are many actions we might want to schedule:

1. Database backups (feat: automated backups w/ AWS S3 #2305)
2. File synchronization (feature: Upload backups to Google Drive #2071) and uploads.
3. Emailing reports on a regular basis ((feat) Email pushing report #1766)
4. Do system checks (such as the "is installed" check in Installation feature for bhima #2299) on reboot.

All of these features require some sort of scheduler that can run at regular intervals such as daily, weekly, and monthly.

A similar feature is already proposed in https://github.com/IMA-WorldHealth/ima-data/issues/61. I'll copy the relevant information here:

Scheduler
We will write a library called "scheduler" that will contain the schedules (monthly, weekly, daily, real time) in cron syntax. This will be stored in an object schedules. Basically:

id	schedule	label	description
1	0 2 * * 0	weekly	Weekly - this runs once a week at 2AM on Sunday

We would find a library for Node that handles schedules in a CRON syntax - like node-cron. We would write a small wrapper that allows any modules to use a schedule like this:

const scheduler = require('./lib/scheduler');

scheduler.daily(() => {
  console.log('I will be logged daily');
});

scheduler.weekly(() => {
  console.log('I get fired weekly.');
});

scheduler.custom('* * * * *', () > {
  console.log('I do something every minute');
});

Our backup scripts, email scripts, and anything else we want to schedule would be able to just import the scheduler and then use it as it.

[jniles]

This was taken care of by adding a dependency on TaskList.