DefinitionMergeService should honor overlapping module paths

It is currently possible to specify multiple overlapping autoexport:modules mappings, such that:

1. / => application
2. /content/documents/main/ => development
3. /content/documents/main/production-data => application

This doesn't consistently work as expected, since the module-to-path mappings are not kept in the order specified, and DefinitionMergeService.getModuleByAutoExportConfig() uses a "first match wins" algorithm.

I think a single-line fix to store the mappings with a LinkedHashMap should result in the desired behavior.