Make DebuggerStepThrough attributes consistent

... and add missing intellisense

src/Polly.Shared/Caching/CachePolicy.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using System.Linq;
 using System.Threading;
 using Polly.Utilities;
@@ -51,6 +52,7 @@ internal CachePolicy(
         /// <param name="context">Execution context that is passed to the exception policy; defines the cache key to use in cache lookup.</param>
         /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>The value returned by the action, or the cache.</returns>
+        [DebuggerStepThrough]
         public override TResult ExecuteInternal<TResult>(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken)
         {
             return CacheEngine.Implementation<TResult>(

src/Polly.Shared/Caching/CachePolicyAsync.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using System.Linq;
 using System.Threading;
 using System.Threading.Tasks;
@@ -43,6 +44,7 @@ internal CachePolicy(
         /// <param name="cancellationToken">The cancellation token.</param>
         /// <param name="continueOnCapturedContext">Whether to continue on a captured synchronization context.</param>
         /// <returns>The value returned by the action, or the cache.</returns>
+        [DebuggerStepThrough]
         public override Task<TResult> ExecuteAsyncInternal<TResult>(Func<Context, CancellationToken, Task<TResult>> action, Context context, CancellationToken cancellationToken, bool continueOnCapturedContext)
         {
             return CacheEngine.ImplementationAsync<TResult>(

src/Polly.Shared/Fallback/FallbackPolicy.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Threading;
 
 namespace Polly.Fallback
@@ -22,6 +23,7 @@ internal FallbackPolicy(Action<Action<Context, CancellationToken>, Context, Canc
         /// <param name="context">Execution context that is passed to the exception policy; defines the cache key to use in cache lookup.</param>
         /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>The value returned by the action, or the cache.</returns>
+        [DebuggerStepThrough]
         public override TResult ExecuteInternal<TResult>(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken)
         {
           throw new InvalidOperationException($"You have executed the generic .Execute<{nameof(TResult)}> method on a non-generic {nameof(FallbackPolicy)}.  A non-generic {nameof(FallbackPolicy)} only defines a fallback action which returns void; it can never return a substitute {nameof(TResult)} value.  To use {nameof(FallbackPolicy)} to provide fallback {nameof(TResult)} values you must define a generic fallback policy {nameof(FallbackPolicy)}<{nameof(TResult)}>.  For example, define the policy as Policy<{nameof(TResult)}>.Handle<Whatever>.Fallback<{nameof(TResult)}>(/* some {nameof(TResult)} value or Func<..., {nameof(TResult)}> */);");

src/Polly.Shared/Policy.cs

@@ -86,7 +86,7 @@ public void Execute(Action<Context> action, Context context)
         }
 
         /// <summary>
-        /// 
+        /// Executes the specified action within the policy
         /// </summary>
         /// <param name="action"></param>
         /// <param name="cancellationToken"></param>

src/Polly.Shared/Wrap/PolicyWrap.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using System.Threading;
 using Polly.Utilities;
 
@@ -37,6 +38,7 @@ internal PolicyWrap(Action<Action<Context, CancellationToken>, Context, Cancella
         /// <param name="context">Execution context that is passed to the exception policy; defines the cache key to use in cache lookup.</param>
         /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>The value returned by the action, or the cache.</returns>
+        [DebuggerStepThrough]
         public override TResult ExecuteInternal<TResult>(Func<Context, CancellationToken, TResult> action, Context context, CancellationToken cancellationToken)
         {
             return PolicyWrapEngine.Implementation<TResult>(

src/Polly.Shared/Wrap/PolicyWrapAsync.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Diagnostics;
 using System.Threading;
 using System.Threading.Tasks;
 using Polly.Utilities;
@@ -23,6 +24,7 @@ internal PolicyWrap(Func<Func<Context, CancellationToken, Task>, Context, Cancel
         /// <param name="cancellationToken">The cancellation token.</param>
         /// <param name="continueOnCapturedContext">Whether to continue on a captured synchronization context.</param>
         /// <returns>The value returned by the action, or the cache.</returns>
+        [DebuggerStepThrough]
         public override Task<TResult> ExecuteAsyncInternal<TResult>(Func<Context, CancellationToken, Task<TResult>> action, Context context, CancellationToken cancellationToken, bool continueOnCapturedContext)
         {
             return PolicyWrapEngine.ImplementationAsync<TResult>(