Avoid unnecessary dependencies on @glimmer types

[dfreeman]

The published types from this package rely on @glimmer/interfaces in two places:

• in the signature of render() to represent that it can accept a component
• in the signature of the internal getComponentManager helper

This PR updates the signature of render() to simply accept any object as its first parameter. This is actually more accurate than the current type—at runtime, render() only requires that the object it receives is either a template or is some object with a component manager, but "has a component manager" isn't something we're able to model in the TS type system.

It also updates the return type of the getComponentManager utility to unknown, as we never actually interact with the manager, we only check for its existence. (In reality this change is likely unnecessary since this .d.ts file won't end up in the import path for consumers using public APIs, but updating this removes references to @glimmer/interfaces in the built types directory entirely.)