chore: fix strict psalm and rector

[susnux]

• split from refactor(appstore): split appstore from settings app #59997

Summary

• As cherry picked psalm changes to also cover tests and make use of the phpunit plugin.
• Fix the strict rector rules to properly autoload OCP otherwise it does not know about those interface¹
• Fix the strict psalm rules for the same reason to make them aware of our OC and OCP code
• Apply the changes and committed the results

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)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

AI (if applicable)

• The content of this PR was partly or fully generated using AI