Fix EZP-23459: eZContentObjectTreeNodeOperations::move missing features

Ensure that it checks whether view caching is enabled before clearing it.
Ensure that CacheThreshold is respected, if exceeded clear all cache.

Improved:
- eZContentCacheManager::clearContentCacheIfNeeded() does already check for ViewCaching enabled
- eZContentCache::inCleanupThresholdRange( $count ) could be used to verify threshold
Merge pull request #1093 from glye/ezp-23459_move_large_subtrees

Fix EZP-23459: eZContentObjectTreeNodeOperations::move missing features