* Removing obsoleted code from MigrationPlanExecutor.cs & Interface
* Removing obsoleted code from EmailAddressPropertyEditor.cs
* Removing obsoleted class CacheRebuilder.cs
* Removing obsoleted code from TextBuilder.cs
* Removing obsoleted class ICacheRebuilder.cs
* Removing obsoleted code from SerilogLogger.cs
* Removing the use of Infrastructure IBackgroundTaskQueue.cs and replacing usage with the Core replacement
* Removing obsoleted code from the FileUploadPropertyEditor.cs
* Removing obsoleted code from BlockValuePropertyValueEditorBase.cs
* Removing obsoleted constructors and methods from MultiNodeTreePickerPropertyEditor.cs and TextHeaderWriter.cs
* Removing obsoleted code from CacheInstructionService.cs
* Bumping obsoleted code from MigrationBase.cs to V18
* Removing obsoleted code from EmailSender.cs
* Removing obsoleted code from BlockEditorVarianceHandler.cs
* Removing obsoleted code from IBackOfficeApplicationManager.cs
* Removing obsoleted code from RedirectTracker.cs & RichTextEditorPastedImages.cs
50ae48b0a2