Bugfix: Accessing AsyncComputed status property should trigger computed function

[aomarks]

Same as value, error, and complete already do. Otherwise, only reading status isn't sufficient for a dependency to get tracked.

[justinfagnani]

Oh, this behavior was somewhat intentional. I think I just copied the comment that mentioned that status ran the function incorrectly.

The idea is that while value and error don't really make sense to access if the function has never run, you may want to access status to see if the task has be initiated. Otherwise the initial state is very hard to ever observe.

I think we should keep an eye on this and see if anyone wants a non-triggering status getter. Maybe there's a separate getter for that.

[justinfagnani]

The class comment should be updated too, since it doesn't mention status:

 * Compute functions are run when the `value`, `error`, or `complete` properties
 * are read, or when `get()` or `run()` are called, and are re-run when any
 * signals that they read change.

[aomarks]

The idea is that while value and error don't really make sense to access if the function has never run, you may want to access status to see if the task has be initiated. Otherwise the initial state is very hard to ever observe.

Ah, I see. I found it surprising that accessing complete would trigger a run, but status didn't, so I figured this was an oversight. How about peekStatus for the side-effect free version?