move TokenRetrieval to api

src/Core/IdentityServer/TokenRetrieval.cs

@@ -1,30 +0,0 @@
-using Microsoft.AspNetCore.Http;
-using System;
-using System.Linq;
-
-namespace Bit.Core.IdentityServer
-{
-    public static class TokenRetrieval
-    {
-        public static Func<HttpRequest, string> FromAuthorizationHeaderOrQueryString(string headerScheme = "Bearer",
-            string qsName = "account_token")
-        {
-            return (request) =>
-            {
-                string authorization = request.Headers["Authorization"].FirstOrDefault();
-
-                if(string.IsNullOrWhiteSpace(authorization))
-                {
-                    return request.Query[qsName].FirstOrDefault();
-                }
-
-                if(authorization.StartsWith(headerScheme + " ", StringComparison.OrdinalIgnoreCase))
-                {
-                    return authorization.Substring(headerScheme.Length + 1).Trim();
-                }
-
-                return null;
-            };
-        }
-    }
-}