Define CM module exports in composer.json, read them for module lookup

Module:
- Has some class files which are prefixed (namespace) with the name of the module
- Configuration
- Update scripts
- Views, layout etc

Namespace:
- Collection of classes with a common prefix
- Can be refactored to "php namespacing" in the future

### Upgrade notes:
Removed:
- Config: testIp, dirData, dirTmp, dirUserfiles
- Const: DIR_LIBRARY

Changed:
- Entrypoints
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