Add finer grained call fail reasons.

The "can dial" method does a lot of complicated checks which end up
boiling down to a not so intuitive error to the user.

Making this better.

Test: Update unit test for can dial basic operation.
Test: Manual test these scenarios.
Bug: 73902028
Bug: 116453747
Change-Id: Ifdf681a1428c7cbb925cdf7f0c66c2d011c3d492