Add mm server bin directory (#13738)

* Add server bin directory needed for build process.

.gitignore

@@ -3,7 +3,6 @@ logs
 .DS_Store
 node_modules
 /dist
-/bin
 /webapp/dist
 jobserver
 npm-debug.log

bin/.gitignore

@@ -0,0 +1,3 @@
+# Folder required for build process
+*
+!.gitignore