Fix folder size contained in S3 buckets

[artonge]

Folders contained in S3 bucket's are displayed with a size of "Pending".

The following command can get the real size to be displayed, but only for one refresh: php occ files:scan --path "<S3 bucket path>"

Rational (I might be wrong):

1. When running the stat method on the S3 folder, the mtime is always set to 'now'.
2. This leads to the hasUpdated method from Files/Storage/Common.php to always returns true,
3. And to the needsUpdate method in Files/View.php to always returns true too.
4. So the cache gets updated by Files/Cache/Scanner.php every time the folder is acceceed. But it gets updated with a size of -1 because the size for S3 folders is not getting computed and default to -1

Need guidance on how and where we should address this issue :).

[CarlSchwan]

I investigated a similar issue with using Group Folders with the S3 storage with Vincent last week:

• OC\File\Cache\Updater: the update function is never called for the folder itself, only for the preview. It's correctly called for folders outside the group folder
• A S3ObjectStorage uses a NoopScanner, but the GroupFolderStorage uses a normal Scanner. This will probably cause troubles when the Updater::update method is called. Maybe it's the reason why Update is not called but I doubt it.

[PVince81]

ref: nextcloud/groupfolders#1630

but probably not related because the latter is for group folders and the problem with S3 primary happens also without

[artonge]

/backport to stable22

[artonge]

/backport to stable21

[PVince81]

Alright, since the solution covers all the interesting cases let's move forward 👍