Small changes to pipelines (#27704)

- Moved CompletionData to another file and not as a nested type of Pipe
- Follow the file name guidelines for tfm specific implementations

Author: davidfowl

src/System.IO.Pipelines/src/System.IO.Pipelines.csproj

@@ -14,6 +14,7 @@
   <ItemGroup>
     <Compile Include="Properties\InternalsVisibleTo.cs" />
     <Compile Include="System\IO\Pipelines\BufferSegment.cs" />
+    <Compile Include="System\IO\Pipelines\CompletionData.cs" />
     <Compile Include="System\IO\Pipelines\FlushResult.cs" />
     <Compile Include="System\IO\Pipelines\InlineScheduler.cs" />
     <Compile Include="System\IO\Pipelines\IDuplexPipe.cs" />
@@ -34,13 +35,13 @@
     <Compile Include="System\IO\Pipelines\ThrowHelper.cs" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetGroup)'=='netcoreapp'">
-    <Compile Include="System\IO\Pipelines\ThreadPoolScheduler.NetCoreApp21.cs" />
+    <Compile Include="System\IO\Pipelines\ThreadPoolScheduler.netcoreapp.cs" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetGroup)'=='netstandard1.3'">
-    <Compile Include="System\IO\Pipelines\ThreadPoolScheduler.NetStandard13.cs" />
+    <Compile Include="System\IO\Pipelines\ThreadPoolScheduler.netstandard1.3.cs" />
   </ItemGroup>
   <ItemGroup Condition="'$(TargetGroup)'=='netstandard'">
-    <Compile Include="System\IO\Pipelines\ThreadPoolScheduler.NetStandard.cs" />
+    <Compile Include="System\IO\Pipelines\ThreadPoolScheduler.netstandard.cs" />
   </ItemGroup>
   <ItemGroup>
     <Reference Include="System.Buffers" />

src/System.IO.Pipelines/src/System/IO/Pipelines/CompletionData.cs

@@ -0,0 +1,24 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Threading;
+
+namespace System.IO.Pipelines
+{
+    internal readonly struct CompletionData
+    {
+        public Action<object> Completion { get; }
+        public object CompletionState { get; }
+        public ExecutionContext ExecutionContext { get; }
+        public SynchronizationContext SynchronizationContext { get; }
+
+        public CompletionData(Action<object> completion, object completionState, ExecutionContext executionContext, SynchronizationContext synchronizationContext)
+        {
+            Completion = completion;
+            CompletionState = completionState;
+            ExecutionContext = executionContext;
+            SynchronizationContext = synchronizationContext;
+        }
+    }
+}

src/System.IO.Pipelines/src/System/IO/Pipelines/Pipe.cs

@@ -845,21 +845,5 @@ public void Reset()
                 ResetState();
             }
         }
-
-        internal readonly struct CompletionData
-        {
-            public Action<object> Completion { get; }
-            public object CompletionState { get; }
-            public ExecutionContext ExecutionContext { get; }
-            public SynchronizationContext SynchronizationContext { get; }
-
-            public CompletionData(Action<object> completion, object completionState, ExecutionContext executionContext, SynchronizationContext synchronizationContext)
-            {
-                Completion = completion;
-                CompletionState = completionState;
-                ExecutionContext = executionContext;
-                SynchronizationContext = synchronizationContext;
-            }
-        }
     }
 }

src/System.IO.Pipelines/src/System/IO/Pipelines/PipeAwaitable.cs

@@ -56,7 +56,7 @@ public CancellationTokenRegistration AttachToken(CancellationToken cancellationT
         }
 
         [MethodImpl(MethodImplOptions.AggressiveInlining)]
-        public void Complete(out Pipe.CompletionData completionData)
+        public void Complete(out CompletionData completionData)
         {
             Action<object> currentCompletion = _completion;
             _completion = s_awaitableIsCompleted;
@@ -66,7 +66,7 @@ public void Complete(out Pipe.CompletionData completionData)
             if (!ReferenceEquals(currentCompletion, s_awaitableIsCompleted) &&
                 !ReferenceEquals(currentCompletion, s_awaitableIsNotCompleted))
             {
-                completionData = new Pipe.CompletionData(currentCompletion, _completionState, _executionContext, _synchronizationContext);
+                completionData = new CompletionData(currentCompletion, _completionState, _executionContext, _synchronizationContext);
             }
         }
 
@@ -90,7 +90,7 @@ public void Reset()
             }
         }
 
-        public void OnCompleted(Action<object> continuation, object state, ValueTaskSourceOnCompletedFlags flags, out Pipe.CompletionData completionData, out bool doubleCompletion)
+        public void OnCompleted(Action<object> continuation, object state, ValueTaskSourceOnCompletedFlags flags, out CompletionData completionData, out bool doubleCompletion)
         {
             completionData = default;
 
@@ -120,18 +120,18 @@ public void OnCompleted(Action<object> continuation, object state, ValueTaskSour
 
             if (ReferenceEquals(awaitableState, s_awaitableIsCompleted))
             {
-                completionData = new Pipe.CompletionData(continuation, state, _executionContext, _synchronizationContext);
+                completionData = new CompletionData(continuation, state, _executionContext, _synchronizationContext);
                 return;
             }
 
             if (!ReferenceEquals(awaitableState, s_awaitableIsNotCompleted))
             {
                 doubleCompletion = true;
-                completionData = new Pipe.CompletionData(continuation, state, _executionContext, _synchronizationContext);
+                completionData = new CompletionData(continuation, state, _executionContext, _synchronizationContext);
             }
         }
 
-        public void Cancel(out Pipe.CompletionData completionData)
+        public void Cancel(out CompletionData completionData)
         {
             Complete(out completionData);
             _canceledState = completionData.Completion == null ?