Implement storing of the metadata linking iOS Live Photos files and respect them on DAV operations applying the same DAV operation to the respective other file.

• Allow clients to set a livephoto metadata in the OC\Metadata API through WebDAV. This metadata is set for the two files and contains the fileid of the other file. Another solution would be to use a header, but not a fan of multiplying custom headers. Also, allowing clients to write the livephotos metadata allows writing it for already uploaded files
• Add listeners to react to Node*Event -
  • NodeDeletedEvent to remove the second file
  • NodeRenamedEvent to rename the second file
    • BeforeNodeRenameEvent to block the operation if one of the two files cannot be renamed (ex: file with the same name at the location, or quota limitation, or … ?)
    • Test when renamed file is a share
  • NodeCopiedEvent to copy the second file
    • BeforeNodeCopiedEvent to block the operation if one of the two files cannot be copied (ex: file with the same name at the location, or quota limitation, or … ?)
    • Test when renamed file is a share
• Optional: block write permissions on the .jpg to prevent inconsistencies?