Fix and re-enable Editing failing feature tests.

https://dev.azure.com/dnceng/internal/_git/dotnet-wpf-test/pullrequest/1739?_a=overview disables failing tests.

**The following test cases were disabled as they fail in .NET Core. They pass in .NET Framework:**
/Name="CaretBrushRenderingStyleAndTriggerTest" /SubArea="Caret"
/Name="CutCopyPasteInTbRtbWithPropertySet1" /SubArea="Clipboard"
/Name="CutCopyPasteInTbRtbWithPropertySet3" /SubArea="Clipboard"
/Name="TextInvalidStyleCase" /SubArea="Controls"
/Name="DataObjectAdvising" /SubArea="DataObject"
/Name="DataObjectAPITest1" /SubArea="DataObject"
/Name="DataObjectAPITest6" /SubArea="DataObject"
/Area="Editing" /Name="IMETextCompositionVerification_Japanese" /SubArea="IME"
/Name="IMEInputOverMixedContent_Japanese" /SubArea="IME"
/Name="IMETextSelectionTest_Japanese" /SubArea="IME"
/Name="IMETypingOverSelection_Japanese" /SubArea="IME"
/Name="IMEMaxLengthTest_Japanese" /SubArea="IME"
/Name="IMEInsertDeleteTest_Japanese" /SubArea="IME"
/Name="SetPreferredImeConversionModeTest" /SubArea="IME"
/Name="DataObjectLockDown2" /SubArea="PartialTrust"
/Name="DragDropEvents2" /SubArea="PartialTrust"
/Name="GrabHandleAdornerBVTTest2" /SubArea="PartialTrust"
/Name="HyperlinkTest2" /SubArea="PartialTrust" /Name="ListFlowDirection2" /SubArea="PartialTrust"
/Name="ProgrammaticAccessToClipBoardInPTTest" /SubArea="PartialTrust"
/Name="SpellingReformTest1" /SubArea="PartialTrust"
/Name="TestClearValueForDataBoundValues2" /SubArea="PartialTrust"
/Name="TextBoxGetRectFromCharIndex2" /SubArea="PartialTrust"
/Name="TextBoxScrollFunctionTest2" /SubArea="PartialTrust"
/Name="TextRangeSaveLoadTest1" /SubArea="PartialTrust"
/Name="CustomSpellerDictionary_PartialTrust" /SubArea="Speller"
/Name="CustomSpellerDictionaryInvalidInPTTest" /SubArea="Speller"
/Name="SpellerTest" /SubArea="Speller"
/Name="SpellerTestMultipleLangOnRTB" /SubArea="Speller"
/Name="SpellerTestOnTB" /SubArea="Speller"
/Name="SpellerWordSelectionTest" /SubArea="Speller"
/Name="SpellingReformTest" /SubArea="Speller"
/Name="TextBoxGetRectFromCharIndex1" /SubArea="TextBox"
/Name="TextBoxMinMaxLinesInDifferentContainersForDisplayMode" /SubArea="TextBox"
/Name="TextBoxBaseScrollFunctionsLineTests" /SubArea="TextBoxBase"
/Name="TextBoxLineUpLineDownTests" /SubArea="TextBoxBase"
/Name="TextBoxVisualAutomation" /SubArea="TextBox"
/Name="RichTextBoxReadInDiffThreads" /SubArea="TextOM"

**The following are related to known issue: https://github.com/dotnet/wpf/issues/579**
/Name="ClipboardTestInCrossContainer1" /SubArea="Clipboard"
/Name="ClipboardTestInCrossContainer3" /SubArea="Clipboard"
/Name="ClipboardTestInSameContainer2" /SubArea="Clipboard"
/Name="ClipboardTestInSameContainer4" /SubArea="Clipboard"
/Name="CutCopyPasteInTbRtbWithPropertySet2" /SubArea="Clipboard"
/Name="DataTransferExtensibilityTest" /SubArea="Clipboard"
/Name="ImageCopyPasteTest" /SubArea="Clipboard"
/Name="InvalidClipboardTest" /SubArea="Clipboard"
/Name="XamlPackageBVTTest" /SubArea="Clipboard"
/Name="ContextMenuTest" /SubArea="Controls"
/Name="TextInvalidStyleCase" /SubArea="Controls"
/Name="CommandServiceClipboardQuery" /SubArea="Editor"
/Name="DataTransferScripts" /SubArea="Editor"
/Name="EditCommandText" /SubArea="Editor"
/Name="KeyboardActionCases" /SubArea="Editor"
/Name="TextEditorKeyboardEditing" /SubArea="Editor"
/Name="BidiEditingTestCases" /SubArea="RichEditing"
/Name="HyperlinkRegressionTest" /SubArea="RichEditing"
/Name="HyperlinkTest1" /SubArea="RichEditing"
/Name="ParagraphEditingTestWithKeyboard" /SubArea="RichEditing"
/Name="ParagraphEditingWithMouse2" /SubArea="RichEditing"
/Name="PargraphDeletingAndMergingBVT" /SubArea="RichEditing"
/Name="FlowDocumentProperties" /SubArea="RichTextBox"
/Name="RichTextBoxFlowDocument" /SubArea="RichTextBox"
/Name="RichTextRegressionTest" /SubArea="RichTextBox"
/Name="SelectionCases" /SubArea="Selection"
/Name="TableSelectionsTest2" /SubArea="TableEditing"
/Name="TestForProgrammaticChangeInReadOnlyControl" /SubArea="TextBox"
/Name="BackgroundLayoutControls" /SubArea="TextBoxBase"
/Name="TextBoxOMCutCopyPaste" /SubArea="TextBoxBase"
/Name="TextElementExtractUndoWithExpressions" /SubArea="TextOM"
/Name="TextRangeSaveLoadTest" /SubArea="TextOM"
/Name="EmbeddedObjectUndoRedo" /SubArea="UndoRedo"
/Name="UndoEmbededObjectTest" /SubArea="UndoRedo"
/Name="RtfToXamlPredicates" /SubArea="XamlRtf"
/Name="RtfXamlViewBVT" /SubArea="XamlRtf"
/Name="XamlToRtfTest1" /SubArea="XamlRtf"

**The following fail in .NET Framework as well, but are disabled here:**
/Name="IMEConversionModeTest_ChinesePinyin" /SubArea="IME"
/Name="IMEInputOverMixedContent_ChineseNewPhonetic" /SubArea="IME"
/Name="IMEInputOverMixedContent_ChinesePinyin" /SubArea="IME"
/Name="IMEInputOverMixedContent_ChineseQuanPin" /SubArea="IME"
/Name="IMEInsertDeleteTest_ChineseNewPhonetic" /SubArea="IME"
/Name="IMEMaxLengthEventsTest_ChinesePinyin" /SubArea="IME"
/Name="IMEMaxLengthEventsTest_ChineseQuanPin" /SubArea="IME"
/Name="IMEMaxLengthTest_ChinesePinyin" /SubArea="IME"
/Name="IMEMaxLengthTest_ChineseQuanPin" /SubArea="IME"
/Name="IMETextCompositionVerification_ChineseNewPhonetic" /SubArea="IME"
/Name="IMETextSelectionTest_ChineseNewPhonetic" /SubArea="IME"
/Name="IMETextSelectionTest_ChineseQuanPin" /SubArea="IME"
/Name="IMETypingOverSelection_ChinesePinyin" /SubArea="IME"
/Name="IMEUndoRedoTest_ChineseNewPhonetic" /SubArea="IME"
/Name="IMEUndoRedoTest_ChinesePinyin" /SubArea="IME"
/Name="IMEUndoRedoTest_ChineseQuanPin" /SubArea="IME"
/Name="IMEVerifyAutoFinalization_ChineseNewPhonetic" /SubArea="IME"
/Name="IMETextCompositionVerification_Japanese" /SubArea="IME"
/Name="IMEInsertDeleteTest_ChinesePinyin" /SubArea="IME"
/Name="IMEMaxLengthUndoTest_ChinesePinyin" /SubArea="IME"
/Name="IMEMaxLengthUndoTest_ChineseQuanPin" /SubArea="IME"
/Name="IMETextCompositionVerification_ChinesePinyin" /SubArea="IME”
/Name="IMETextSelectionTest_ChinesePinyin" /SubArea="IME"
/Name="IMEVerifyAutoFinalization_ChinesePinyin" /SubArea="IME"
/Name="SelectionRenderingStyleAndTriggerTest" /SubArea="Selection"