Determine how weekends should be discovered and treated in commands

[fmartingr]

#discussion

Currently the /trigger tomorrow command displays events for the next natural day, but in most scenarios instead of the next natural day we want the next working day.

There are some handlers in pieces of code that avoid Saturdays and Sundays (for the daily reminder) but this is not for everyone.

The plugin must discover (from the provider configuration for example) or let the user setup their working days and either avoid them under tomorrow or add a new command that controls this behaviour.

Acceptance criteria

• Determine how we can let/discover working days for users.
• Determine if we should modify the tomorrow subcommand behaviour or create a new command.
• Document findings in a new issue to handle the task.