Merge a "runtime module" diff into the appropriate modules for auto-export

This is a part of the full implementation of HCM-80 aka REPO-1685.

Given a "runtime" ModuleImpl containing a single ConfigSource and zero or more ContentSources, plus a baseline ConfigurationModel and the auto-export config, produce new copies of the Modules to be auto-exported that would produce the same effect as applying the previous version and the new "runtime" ModuleImpl in sequence. (This cumulative effect should also be the same as the current runtime configuration R, assuming the previous steps of the auto-export process were correct.)

The merged representation should take into account the previous Sources and Definitions, so that the representations of JCR nodes and properties generally remain in the same Source and Definition as the previous version. When a new, unrelated Definition must be created, the rules defined in org.onehippo.cms7.autoexport.LocationMapper should be respected, where possible. Otherwise, all ConfigDefinitions should be combined into a single "main.yaml" Source, and ContentDefinitions should be placed in new Sources with unique, generated names.