Implement an internal cache for ObjectService
Implement an internal cache for ObjectService

This change adds internal caching of returned object data in ObjectService, allowing the service to avoid external requests when those are not required. Respects context variables when storing/retrieving - any change in method arguments which would cause a different result will also cache that result separately by context. Flushing the cache can only happen by flushing all cached object data, due to the way CMIS objects may be returned as nested object data of other requests.

Behavior and reasoning behind flushing is further documented in cache flush method.

dkd/php-cmis-client