Correctly set access modifiers

[JamieMagee]

Currently, most of our classes are public. This was fine whenever Component Detection wasn't open source. However, now that it is open source, and we try to follow semantic versioning, many changes we make end up being breaking changes, requiring a major version bump, when they should be internal implementation details.

By correctly setting access modifiers, like private and internal, we are free to change implementation details without affecting the public contract.