Clean-up existing routines and migrate from deprecated annotations

Description

This MR contains three separate commits

• Migrate from LifecycleObserver annotations to DefaultLifecycleObserver (resolves deprecation warnings)
• Relocate code which is in folders inconsistent with their package
• Update source code headers

Motivation and Context

This cleans up approximately 18 warnings. There is one code change for an iterator in ExternalSubRepository due to a shadowed it variable. There is an additional flag change for exportSchema to resolve a compiler annotation processor warning.

How Has This Been Tested?

Tested lifecycle events with debugger and they were invoked as expected.

Types of changes

• Enhancement (non-breaking change which cleans up / improves existing functionality)

Checklist

• I have read the CONTRIBUTING section of the README document.