Add persistence to Job Queue

[Guilherme-Vasconcelos]

Describe your idea
Job Queue is currently lost if Aqua turns off. While this isn't a problem for reminders that are only a few minutes after, it may be a problem for reminders scheduled to hours/days later.

Extra information
Suggestion: create a dump file once at the end of the JobQueue loop using pickle:
https://docs.python.org/3/library/pickle.html

Maybe use inspect.getsource: https://stackoverflow.com/questions/12072252/cant-get-source-code-for-a-method-declared-through-exec-using-inspect-in-pyth

Alternatively, instead of each Job having a function to be executed, they could have a type instead (e.g. send_message type), which are easier to store / load.