trace2: move formattargettypes

Move the FormatTargetTypes enum from the specific Trace2StreamWriter class
to the shared Trace2Writer class, since the Trace2FileWriter class also
uses values from this enum.

Author: ldennington

src/shared/Core/ITrace2Writer.cs

@@ -3,6 +3,16 @@
 
 namespace GitCredentialManager;
 
+/// <summary>
+/// The different format targets supported in the TRACE2 tracing
+/// system.
+/// </summary>
+public enum Trace2FormatTarget
+{
+    Event,
+    Normal
+}
+
 public interface ITrace2Writer : IDisposable
 {
     bool Failed { get; }

src/shared/Core/Trace2StreamWriter.cs

@@ -3,16 +3,6 @@
 
 namespace GitCredentialManager;
 
-/// <summary>
-/// The different format targets supported in the TRACE2 tracing
-/// system.
-/// </summary>
-public enum Trace2FormatTarget
-{
-    Event,
-    Normal
-}
-
 public class Trace2StreamWriter : Trace2Writer
 {
     private readonly TextWriter _writer;