perf(external-share): Port to Entity and use snowflake Ids

[CarlSchwan]

• Port away from Files::buildNotExistingFileName
• Use IUser and IGroup instead of plain string

• Resolves: #

Summary

TODO

• [ ] ...

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• [x] 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)
• [x] Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• [x] Milestone added for target branch/version (ex: 32.x for stable32)

[come-nc]

According to integation tests you broke federated shares @CarlSchwan