feat: make use of the partial file tree fetching implemented in the b…

[Sparkier]

…ackend

fix https://github.com/OpenDevin/OpenDevin/issues/1136

[Sparkier]

This implementation does not work with the selection of changed files in the file tree. Selecting changed files would mean we'd have to load that part of the tree on demand which can get very messy considering file changes are populated through actions and state updates.

[Sparkier]

Decided against this since this complicates things a lot and the new file tree implementation solves most of the UX problems.