Allow beIdenticalTo and be matchers to be used as composed matchers

[younata]

Because beIdenticalTo and be are typed to AnyObject, they do not build when used as a composed matcher (e.g. as part of satisfyAnyOf, or map). Which is justifiably rather frustrating.

This is a very small change with no need for documentation. I actually view this as a bugfix change.

This is very similar to what #1173 did, but now to 2 other matchers.

Checklist - While not every PR needs it, new features should consider this list:

• Does this have tests?
• Does this have documentation?
• Does this break the public API (Requires major version bump)?
• Is this a new feature (Requires minor version bump)?