Make the Assets Tree flat

[MrFlashAccount]

Pull Request Description

• Close https://github.com/enso-org/cloud-v2/issues/1656
  • Switch Asset Tree from a tree structure to only show children of this directory
• Close https://github.com/enso-org/cloud-v2/issues/1772
  • Compute paths correctly to display in properties panel on the right side

Important Notes

Checklist

Please ensure that the following checklist has been satisfied before submitting the PR:

• The documentation has been updated, if necessary.
• Screenshots/screencasts have been attached, if there are any visual changes. For interactive or animated visual changes, a screencast is preferred.
• All code follows the
  Scala,
  Java,
  TypeScript,
  and
  Rust
  style guides. In case you are using a language not listed above, follow the Rust style guide.
• Unit tests have been written where possible.
• If meaningful changes were made to logic or tests affecting Enso Cloud integration in the libraries,
  or the Snowflake database integration, a run of the Extra Tests has been scheduled.
  • If applicable, it is suggested to paste a link to a successful run of the Extra Tests.

[mergify]

⚠️ The sha of the head commit of this PR conflicts with #12115. Mergify cannot evaluate rules on this PR. ⚠️

[github-actions]

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[PabloBuchu]

1. Context menu is not working in subdirectory
2. Drag n drop upload always put file in root (either user or team space)
3. I can't drag n drop asset on directory when I am not in root.
4. Drag n drop of datalinks is not working
   5. Please add .. indicating parent directory

[somebody1234]

1, 2, 3 seem already fixed by sergei

[somebody1234]

Drag n drop upload always put file in root

oops this was broken, easy fix though