[FEAT] Run a command after successful sessions

[JaDogg]

Is your feature request related to a problem? Please describe.
Allow users to run an arbitrary command when work/small-break/large-break alarm is triggered

Describe the solution you'd like
3 configurable shell commands & a switch to enable/disable this feature in config. No need for new CLI argument support. Config should load empty commands and disabled command execution if keys are not found

Describe alternatives you've considered
This would allow people to plug in custom notifications, etc.

[JaDogg]

This is already completed