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

src/Api/Controllers/LicensesController.cs

@@ -1,7 +1,7 @@
 using Microsoft.AspNetCore.Mvc;
 using Bit.Core.Services;
 using Microsoft.AspNetCore.Authorization;
-using Bit.Core;
+using Bit.Core.Context;
 using System.Threading.Tasks;
 using Bit.Core.Models.Business;
 using Bit.Core.Exceptions;
@@ -21,7 +21,7 @@ namespace Bit.Api.Controllers
         private readonly IUserService _userService;
         private readonly IOrganizationRepository _organizationRepository;
         private readonly IOrganizationService _organizationService;
-        private readonly CurrentContext _currentContext;
+        private readonly ICurrentContext _currentContext;
 
         public LicensesController(
             ILicensingService licensingService,
@@ -29,7 +29,7 @@ namespace Bit.Api.Controllers
             IUserService userService,
             IOrganizationRepository organizationRepository,
             IOrganizationService organizationService,
-            CurrentContext currentContext)
+            ICurrentContext currentContext)
         {
             _licensingService = licensingService;
             _userRepository = userRepository;