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/Context/InstallationContext.cs

@@ -0,0 +1,23 @@
+using System.Diagnostics.CodeAnalysis;
+using Microsoft.EntityFrameworkCore;
+using Oqtane.Models;
+
+namespace Oqtane.Repository
+{
+    
+    public class InstallationContext : DbContext
+    {
+        private readonly string _connectionString;
+
+        public InstallationContext(string connectionString)
+        {
+            _connectionString = connectionString;
+        }
+
+        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
+            => optionsBuilder.UseSqlServer(_connectionString);
+
+        public virtual DbSet<ApplicationVersion> ApplicationVersion { get; set; }
+        public virtual DbSet<Tenant> Tenant { get; set; }
+    }
+}