Copy encryption keys first and then rename the files

[jvillafanez]

Description

Instead of renaming the file and then move the keys, we'll copy the keys first so we have a chance of reverting the changes if the file fails to be renamed. We either remove the original keys if rename succeeds or the copied keys if it fails.
Worst case, if exception happens and cleanup can't be performed, the file should still be accessible because there are valid keys still in place

Related Issue

https://github.com/owncloud/enterprise/issues/5344

Motivation and Context

This will harden the code and prevent the file from becoming inaccessible if something goes wrong.

How Has This Been Tested?

Manually tested with the steps provided in the related issue.

Screenshots (if appropriate):

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Database schema changes (next release will require increase of minor version instead of patch)
• Breaking change (fix or feature that would cause existing functionality to change)
• Technical debt
• Tests only (no source changes)

Checklist:

• Code changes
• Unit tests added
• Acceptance tests added
• Documentation ticket raised:
• Changelog item, see TEMPLATE

[update-docs]

Thanks for opening this pull request! The maintainers of this repository would appreciate it if you would create a changelog item based on your changes.

[ownclouders]

💥 Acceptance tests pipeline webUIRestrictSharing-chrome-mariadb10.2-php7.4 failed. The build has been cancelled.

https://drone.owncloud.com/owncloud/core/37091/132

[jvillafanez]

Copying the keys will change the fileid of the keys in the filecache. This shouldn't be a problem though. It should work regardless of the actual storage. In fact, it's questionable to have the data in the filecache; it's seems a side effect of the tools used, and it seems to work even if the data is removed from the filecache table.

[pako81]

@jvillafanez grab some reviewers?

[IljaN]

LGTM 👍 @DeepDiver1975 Could you also please have a look as you were recently working with key stuff.

[IljaN]

Please add changelog

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
2 Code Smells

87.0% Coverage
0.0% Duplication