Cron tool

[projector22]

Significant revamp of the app's ability to create and manage cron tasks

Ideas

• [ ] handle crons from Windows
• [ ] handle crons from Linux
• [ ] handle crons from service worker
• [ ] service worker, that gets invoked as a defined interval and runs in the background, handling cron chores which are defined as often as required
• [ ] add, edit & remove cron tasks
• [ ] figure out a better system for windows than copying a script into the cli