Database Manager

done:
+ master.sql as resource
+ implemented incremental database changes also for Master
+ dbUp sql script variables implemented
+ improved database handling and creation code
+ simpified database creation
+ almost all Database and Tenant creation moved to DatabaseManager.cs (rest code marked with TODO)
+ Unattended install of master can be performed by settings in appsettings.json
+ Improved IsInstalled checking
+ Removed DBSchema field from Tenant
+ Default database and site creation moved to Program.Main

Oqtane.Server/Repository/SiteTemplateRepository.cs

@@ -41,7 +41,7 @@ namespace Oqtane.Repository
                 var siteTemplateObject = ActivatorUtilities.CreateInstance(_serviceProvider, siteTemplateType);
                 siteTemplate = new SiteTemplate
                 {
-                    Name = (string)siteTemplateType.GetProperty("Name").GetValue(siteTemplateObject),
+                    Name = (string)siteTemplateType.GetProperty("Name")?.GetValue(siteTemplateObject),
                     TypeName = siteTemplateType.AssemblyQualifiedName
                 };
                 siteTemplates.Add(siteTemplate);