Map dotnet_separate_import_directive_groups=false to OptionSetting.Allow

Roslyn does not remove blank lines when dotnet_separate_import_directive_groups is false.

Author: sharwell

StyleCop.Analyzers/StyleCop.Analyzers.Test.CSharp8/Settings/SettingsCSharp8UnitTests.cs

@@ -66,7 +66,7 @@ public async Task VerifyEditorConfigSettingsAreReadCorrectlyAsync()
 
             Assert.NotNull(styleCopSettings.OrderingRules);
             Assert.Equal(UsingDirectivesPlacement.OutsideNamespace, styleCopSettings.OrderingRules.UsingDirectivesPlacement);
-            Assert.Equal(OptionSetting.Omit, styleCopSettings.OrderingRules.BlankLinesBetweenUsingGroups);
+            Assert.Equal(OptionSetting.Allow, styleCopSettings.OrderingRules.BlankLinesBetweenUsingGroups);
         }
 
         [Theory]

StyleCop.Analyzers/StyleCop.Analyzers/Settings/ObjectModel/OrderingSettings.cs

@@ -105,7 +105,7 @@ protected internal OrderingSettings(JsonObject orderingSettingsObject, AnalyzerC
             blankLinesBetweenUsingGroups ??= AnalyzerConfigHelper.TryGetBooleanValue(analyzerConfigOptions, "dotnet_separate_import_directive_groups") switch
             {
                 true => OptionSetting.Require,
-                false => OptionSetting.Omit,
+                false => OptionSetting.Allow,
                 _ => null,
             };