Files app: Change from Entry to FileData in the new DirectoryTree

This is the first CL of a series to update the Directory Tree to not
depend on the Entry type, instead it should use the FileData type.

This is a preparation to onboard a new type called Materialized View
that isn't directly linked to Entry and to start moving away from the
File System API.

Bug: b:327534506
Change-Id: Ic5c845361b77d54dda3df5fb2b4a54295843230b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5333949
Commit-Queue: Luciano Pacheco <lucmult@chromium.org>
Reviewed-by: Wenbo Jie <wenbojie@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1268875}