feat($injector): report circularity in circular dependency error message

Request Type: feature

How to reproduce: 

Component(s): di

Impact: medium

Complexity: small

This issue is related to: 

**Detailed Description:**

Change the error message for a circular dependency to display the full
circle back to the first service being instantiated, so that the problem
is obvious:

    a <- b <- a

The previous message stopped one dependency short of the full
circle:

    b <- a

**Other Comments:**

Changes the content of the cdep error message, which may be considered
a breaking change.