Issue #1: scaffold gateway solution and projects

src/MxGateway.IntegrationTests/IntegrationTestEnvironmentTests.cs

@@ -0,0 +1,12 @@
+namespace MxGateway.IntegrationTests;
+
+public sealed class IntegrationTestEnvironmentTests
+{
+    [Fact]
+    public void LiveMxAccessTests_AreOptInByEnvironmentVariable()
+    {
+        Assert.Equal(
+            "MXGATEWAY_RUN_LIVE_MXACCESS_TESTS",
+            IntegrationTestEnvironment.LiveMxAccessVariableName);
+    }
+}