Add Attribute to use the Bit Autodata dependency chain

BitAutoDataAttribute is used to mark a Theory as autopopulating
parameters.

Extract common attribute methods to to a helper class. Cannot
inherit a common base, since both require inheriting from different
Xunit base classes to work.

test/Common/AutoFixture/Attributes/BitAutoDataAttribute.cs

@@ -0,0 +1,29 @@
+using System;
+using Xunit.Sdk;
+using AutoFixture;
+using System.Reflection;
+using System.Collections.Generic;
+using Bit.Test.Common.Helpers;
+
+namespace Bit.Test.Common.AutoFixture.Attributes
+{
+    public class BitAutoDataAttribute : DataAttribute
+    {
+        private readonly Func<IFixture> _createFixture;
+        private readonly object[] _fixedTestParameters;
+
+        public BitAutoDataAttribute(params object[] fixedTestParameters) :
+            this(() => new Fixture(), fixedTestParameters)
+        { }
+
+        public BitAutoDataAttribute(Func<IFixture> createFixture, params object[] fixedTestParameters) :
+            base()
+        {
+            _createFixture = createFixture;
+            _fixedTestParameters = fixedTestParameters;
+        }
+
+        public override IEnumerable<object[]> GetData(MethodInfo testMethod)
+            => BitAutoDataAttributeHelpers.GetData(testMethod, _createFixture(), _fixedTestParameters);
+    }
+}