feat: add IUserFolder similar to IRootFolder

[susnux]

• Fixes Move getStorageInfo to non-legacy code #52896

Summary

TBD

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[come-nc]

I do not understand these last 4 errors and how to get rid of them 😿

There were 4 errors:
1) OCA\Files_Sharing\Tests\ApiTest::testGetShareFromSourceWithReshares
OCP\Files\NotPermittedException: Could not create folder "/test-share-user2", folder exists but unable to get cache entry
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/Folder.php:143
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/Folder.php:501
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyUserFolder.php:50
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyFolder.php:51
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyFolder.php:65
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyFolder.php:206
/home/runner/actions-runner/_work/server/server/lib/private/Share20/Manager.php:210
/home/runner/actions-runner/_work/server/server/lib/private/Share20/Manager.php:639
/home/runner/actions-runner/_work/server/server/apps/files_sharing/tests/ApiTest.php:523
2) OCA\Files_Sharing\Tests\ApiTest::testGetShareFromFolderReshares
OCP\Files\NotPermittedException: Could not create folder "/test-share-user2", folder exists but unable to get cache entry
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/Folder.php:143
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/Folder.php:501
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyUserFolder.php:50
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyFolder.php:51
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyFolder.php:65
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyFolder.php:206
/home/runner/actions-runner/_work/server/server/lib/private/Share20/Manager.php:210
/home/runner/actions-runner/_work/server/server/lib/private/Share20/Manager.php:639
/home/runner/actions-runner/_work/server/server/apps/files_sharing/tests/ApiTest.php:638
3) OCA\Files_Sharing\Tests\ApiTest::testGetShareMultipleSharedFolder
OCP\Files\NotPermittedException: Could not create folder "/test-share-user2", folder exists but unable to get cache entry
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/Folder.php:[143](https://github.com/nextcloud/server/actions/runs/20283089930/job/58250083307?pr=53048#step:8:144)
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/Folder.php:501
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyUserFolder.php:50
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyFolder.php:51
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyFolder.php:65
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyFolder.php:206
/home/runner/actions-runner/_work/server/server/lib/private/Share20/Manager.php:210
/home/runner/actions-runner/_work/server/server/lib/private/Share20/Manager.php:639
/home/runner/actions-runner/_work/server/server/apps/files_sharing/tests/ApiTest.php:825
4) OCA\Files_Sharing\Tests\EtagPropagationTest::testOwnerUnshares
OCP\Files\NotPermittedException: Could not create folder "/test-share-user2", folder exists but unable to get cache entry
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/Folder.php:143
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/Folder.php:501
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyUserFolder.php:50
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyFolder.php:51
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyFolder.php:65
/home/runner/actions-runner/_work/server/server/lib/private/Files/Node/LazyFolder.php:206
/home/runner/actions-runner/_work/server/server/lib/private/Share20/Manager.php:210
/home/runner/actions-runner/_work/server/server/lib/private/Share20/Manager.php:1107
/home/runner/actions-runner/_work/server/server/lib/private/Share20/Manager.php:1[147](https://github.com/nextcloud/server/actions/runs/20283089930/job/58250083307?pr=53048#step:8:148)
/home/runner/actions-runner/_work/server/server/apps/files_sharing/tests/EtagPropagationTest.php:275

[come-nc]

The remaining failure comes from the fact that when a user folder exists on disk but not in oc_filecache, it fails to be scanned correctly.
This is because of the failsafe in LocalRootScanner the folder is not scanned and this triggers OCP\Files\NotPermittedException: Could not create folder "/test-share-user2", folder exists but unable to get cache entry

Previous code did not have the issue because it did not try to create /user but directly /user/files, I think.
It’s not clear to me whether /user exists in the hierarchy of folders in the node API. It seems previous code passed null as $parent for user folder, but ready the code of getParent that means it will still try to create a node for /user at some point.

@icewind1991 I’m interested by your input on this and whether you think commit d9df76e is a good idea.

[come-nc]

s3 tests are now failing 😭

[come-nc]

I rebased on master and now there are new failures in trashbin tests. I’m unable to reproduce those so far.

[come-nc]

The failure in files_sharing is related to trashbin as well, so the current issue is related to trashbin.
It does not fail on sqlite, somehow.

I could not find a way to reproduce the issue locally.