Added BizTalk build output files to ignore list

VisualStudio.gitignore

@@ -278,4 +278,10 @@ __pycache__/
 # !tools/packages.config
 
 # Telerik's JustMock configuration file
-*.jmconfig
+*.jmconfig
+
+# BizTalk build output
+*.btp.cs
+*.btm.cs
+*.odx.cs
+*.xsd.cs