Add module map for framework

This allows users to directly import Instabug from Swift, without having
to do it in their bridging header.

Author: keith

Instabug.framework/Modules/module.modulemap

@@ -0,0 +1,6 @@
+framework module Instabug {
+  umbrella header "Instabug.h"
+
+  export *
+  module * { export * }
+}