Provide mechanism for managing resources across engines and executions

[YongGoose]

Resolves #2816

Overview

• Designing a class to manage context at the platform level
• Adding a session-level store to LauncherSession
• Adding a request-level store to Launcher
• Exposing the request-level store in EngineDiscoveryRequest and TestPlan
• Utilizing the request-level store in JupiterEngineExtensionContext

---

I hereby agree to the terms of the JUnit Contributor License Agreement.

---

Definition of Done

• There are no TODOs left in the code
• Method preconditions are checked and documented in the method's Javadoc
• Coding conventions (e.g. for logging) have been followed
• Change is covered by automated tests including corner cases, errors, and exception handling
• Public API has Javadoc and @API annotations
• Change is documented in the User Guide and Release Notes