Report cancellation of a suspend action as a result of the suspension

Previously, it was handled as an unexpected error.

Author: MDoerner

Rubberduck.Parsing/VBA/ParseCoordinator.cs

@@ -150,7 +150,13 @@ public void SuspendRequested(object sender, RubberduckStatusSuspendParserEventAr
                     CancellationToken.None);
                 e.BusyAction.Invoke();
             }
-            catch(Exception ex)
+            catch (OperationCanceledException ex)
+            {
+                e.Result = SuspensionResult.Canceled;
+                e.EncounteredException = ex;
+                throw;
+            }
+            catch (Exception ex)
             {
                 e.Result = SuspensionResult.UnexpectedError;
                 e.EncounteredException = ex;

Rubberduck.Parsing/VBA/RubberduckParserState.cs

@@ -88,6 +88,10 @@ public enum SuspensionResult
         /// </summary>
         NotEnabled,
         /// <summary>
+        /// The suspend action has thrown an OperationCanceledException.
+        /// </summary>
+        Canceled,
+        /// <summary>
         /// An unexpected error; usually indicates a bug in code.
         /// </summary>
         UnexpectedError