fix(files): Correctly copy the cache information during copy operations

[artonge]

Needed to copy the encrypted flag of encrypted files when those files are two level down in a moved folder.

Reproduction steps of the issue:

• Set up the following folder structure
  • /A/B/t.txt
  • /C
• Copy A in C
• t.txt is encrypted but does not have the encrypted flag set to true, and therefore not readable.

With this PR, t.txt is readable.

Note: Open to better ways to share code between the two methods.

Added a test to ensure file content stays the same after a copy.

[joshtrichards]

This might help with #48174.

[come-nc]

Kind of 🐘 , I do not understand what’s going on here

[artonge]

Snap, the ObjectStoreStorage does the cache copy inside the storage copy, so the final cache copy creates another filecache entry.

server/lib/private/Files/ObjectStore/ObjectStoreStorage.php

Lines 699 to 700 in 6a0e117

	$targetId = $cache->copyFromCache($cache, $sourceEntry, $to);

Edit: maybe this part can be improved:

server/lib/private/Files/Cache/Updater.php

Lines 203 to 206 in 6a0e117

	if ($this->cache->inCache($target)) {
	$this->cache->remove($target);
	}

[icewind1991]

This introduced a regression for some cross-storage moves, see #49695