[ENH] file galleries: direct mapping mode through flysystem

• initial support for local/ftp/sftp/s3/webdav adapters (TODO: s3 aws sdk not bundled in vendor_bundled used aws sdk package in Tiki packages)
• sync existing external structure to Tiki file galleries and files (TODO: add command for scheduled sync and UI elements or pref to auto-sync on listing load)
• automatically keep mapped file galleries in sync when modifying from Tiki (create/rename/delete directory)
• automatically keep mapped files in sync - rename, upload new file, replace file, delete