feat: Add unit tests and fakes for Crestron environment and data store

- Introduced `FakeCrestronEnvironment` and `FakeEthernetHelper` for testing purposes.
- Implemented `InMemoryCrestronDataStore` to facilitate unit tests for data storage.
- Created `DebugServiceTests` to validate the behavior of debug-related services.
- Added project files for unit tests targeting .NET 9.0 with necessary dependencies.
- Developed production adapters (`CrestronConsoleAdapter`, `CrestronDataStoreAdapter`, `CrestronEnvironmentAdapter`, `CrestronEthernetAdapter`) to interface with the Crestron SDK.
- Updated `Debug` class to utilize injected service abstractions instead of direct SDK calls.
- Enhanced `ControlSystem` initialization to register service adapters before usage.

src/PepperDash.Core.Abstractions/IEthernetHelper.cs

@@ -0,0 +1,16 @@
+namespace PepperDash.Core.Abstractions;
+
+/// <summary>
+/// Abstracts <c>Crestron.SimplSharp.CrestronEthernetHelper</c> to allow unit testing
+/// without the Crestron SDK.
+/// </summary>
+public interface IEthernetHelper
+{
+    /// <summary>
+    /// Returns a network parameter string for the specified adapter.
+    /// </summary>
+    /// <param name="parameter">The parameter to retrieve.</param>
+    /// <param name="ethernetAdapterId">Ethernet adapter index (0 = LAN A).</param>
+    /// <returns>String value of the requested parameter.</returns>
+    string GetEthernetParameter(EthernetParameterType parameter, short ethernetAdapterId);
+}