perf: Implement streaming XML parsing and improve file upload collision handling

[dmiales]

Problem:
Users with large photo and video libraries (5000+ files per folder) experience severe performance issues and OutOfMemoryError (OOM) crashes when opening folders. The application receives a massive XML file from the server and attempts to parse it entirely in memory, causing:

• Application freezes and lagging (observed on Samsung S23+)
• OOM errors during XML parsing
• OOM errors in background synchronization processes
• Data loss due to crashes during sync operations

Solution:
Rewrote the parsing block from the old ownCloud approach to a new streaming parser implementation. Additionally implemented batch processing for folders. This eliminates OOM errors and significantly improves performance and stability, even with 20,000+ photos and videos in a single folder.

Implementation details:

• Add StreamingReadFolderRemoteOperation for memory-efficient folder reading using SAX parser
• Add PropFindSaxHandler for streaming XML parsing of PROPFIND responses
• Prevent OutOfMemoryError for folders with thousands of files by avoiding full XML loading
• Integrate streaming parser into RefreshFolderOperation with fallback to legacy method
• Add batch processing for large folders (500 files per batch) in FileDataStorageManager
• Improve file upload collision handling in UploadFileOperation
  • Add content comparison for non-encrypted files when SKIP policy is used
  • Report SYNC_CONFLICT when file with same name has different content
  • Preserve old behavior for encrypted files and edge cases
• Improve logging levels and add thread name tracking for better debugging