Review commands now show completion status

Review command completion status

CodeRabbit now updates the command acknowledgment for @coderabbitai review and @coderabbitai full review after the requested review finishes.

The status now changes from Review triggered. to Review finished., or from Full review triggered. to Full review finished.

This makes it easier to tell whether a manual review command has only started or has fully completed. See the review commands reference for command usage.