Allow tasks to mark off multiple habits

[thehale]

One happy user has a unique system with several tasks that each correspond 1-1 with a habit. But this user also has an extra "All Habits" counter that should increment whenever any task is completed.

If a task's completion could be configured to send multiple signals to Loop Habit tracker, then this user could map each task to both its dedicated habit and the special "All Habits" counter.

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Technically that should be very doable, including in a backwards compatible way. Essentially each task will need to map to an array of habit actions. We can either write a migration to add that all at one, or update the schema to support single/multiple mappings.

The UI will be a bit trickier, since each task entry's height is no longer guaranteed to be the same. I may even move the setup to a separate screen to hold the many different options that will be available (add new habit, test each habit in isolation, test all together, etc.)

[bfernw]

Great work. Thanks for your effort. Looks like a useful feature I would use it.