refactor: replace GoDotLog with Chickensoft.Log

[wlsnmrk]

Updates GoDotTest to use the new Chickensoft.Log package instead of GoDotLog.

• Bump .NET to v8
• Replace PackageReference GoDotLog -> Chickensoft.Log
• Replace using statements GoDotLog -> Chickensoft.Log
• Replace GDLog(name) with Log(name, new TraceWriter()) to support output in VSCode, VS, and Godot
• Add logic to GoTest.RunTests() to optionally add a DefaultTraceListener to Trace.Listeners, to enable echoing output to Visual Studio's Output pane. This logic also removes the DefaultTraceListener in a finally block, in case multiple calls to GoTest.RunTests() take place (as in the test suite for this package). The option to add DefaultTraceListener is enabled disabled by default.
• Add a TraceListenerManager class implementing IDisposable that optionally adds a DefaultTraceListener to the global trace-listeners collection in its constructor, and removes the listener when disposed. Add a TraceListenerManager in a using to GoTest.RunTests() to optionally add a DefaultTraceListener before running tests and remove it after.
• Add a new command-line switch that prevents enables the DefaultTraceListener. VSCode gets doubled output if DefaultTraceListener is added, presumably from listening to both Trace and to Godot's console output of the same Trace, so this option should be enabled skipped in VSCode settings to avoid the doubled output. (Godot outputs Trace to console by registering its own listener and then echoing that data to console.)
• Add Visual-Studio launch configuration files. The test-project configuration uses the new command-line switch to enable the DefaultTraceListener and thereby provide output when debugging in Visual Studio.
• Update README to include launch profiles for Visual Studio and a description of the new command-line switch.

WIth these changes, GoDotTest output appears in Godot, Visual Studio, and VSCode: