[Files app] Delay expansion of SMB files shares

SMB file shares are a network file system and when they're root is
expandedin Files app all subsequent child folders are queried to
identify if a caret should be rendered beside the folder to enable
expansion in the directory tree. This can cause performance issues much
like FSP volumes, so delay expansion the same way provided file systems
do.

Bug: None
Test: CQ & closure_compile
Change-Id: I787fce89666f9e56ea0a010fb14c6eca529320e5
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3956349
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Commit-Queue: Ben Reich <benreich@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1060880}