New: Guest Role

coscine/issues#2287
coscine/issues#2374

DO NOT MERGE UNTIL EPIC IS DONE

src/Migrations/Migrations/Migration202211031301GuestRole.cs

+using FluentMigrator;
+
+namespace Coscine.Migrations.Migrations
+{
+    //yyyymmddhhmm
+    [Migration(202211031301)]
+    public class Migration202211031301GuestRole : Migration
+    {
+        public override void Down()
+        {
+            Delete.FromTable("Roles").Row(new { DisplayName = "Guest", Description = "Guest of the project." });
+        }
+
+        public override void Up()
+        {
+            Insert.IntoTable("Roles").Row(new { DisplayName = "Guest", Description = "Guest of the project." });
+        }
+    }
+}
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