Add disable send policy (#1130)

* Add Disable Send policy

* Test DisableSend policy

* PR Review

* Update tests for using CurrentContext

This required making an interface for CurrentContext and mocking out
the members used. The interface can be expanded as needed for tests.

I moved CurrentContext to a folder, which changes the namespace
and causes a lot of file touches, but most are just adding a reference

* Fix failing test

* Update exemption to include all exempt users

* Move all CurrentContext usages to ICurrentContext

* PR review. Match messaging with Web

test/Core.Test/AutoFixture/CurrentContextFixtures.cs

@@ -0,0 +1,39 @@
+using System;
+using System.Collections.Generic;
+using AutoFixture;
+using AutoFixture.Kernel;
+using Bit.Core.Context;
+
+namespace Bit.Core.Test.AutoFixture.CurrentContextFixtures
+{
+    internal class CurrentContext : ICustomization
+    {
+        public void Customize(IFixture fixture)
+        {
+            fixture.Customizations.Add(new CurrentContextBuilder());
+        }
+    }
+
+    internal class CurrentContextBuilder : ISpecimenBuilder
+    {
+        public object Create(object request, ISpecimenContext context)
+        {
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+            if (!(request is Type typeRequest))
+            {
+                return new NoSpecimen();
+            }
+            if (typeof(ICurrentContext) != typeRequest)
+            {
+                return new NoSpecimen();
+            }
+
+            var obj = new Fixture().WithAutoNSubstitutions().Create<ICurrentContext>();
+            obj.Organizations = context.Create<List<CurrentContentOrganization>>();
+            return obj;
+        }
+    }
+}