fix: Handle utf-8 file paths on Windows

[taratatach]

Although the WindowsBackend uses unicode aware Windows file API
functions when processing events, it does not do so when searching
directories and their content when creating a new Subscription.
This results in invalid file paths stored in the subscription's tree
when the file name contains non-ascii UTF-8 characters and thus,
dropped events when they rely on the existance of a dir entry with the
valid path.

e.g. consider, we have a directory dir/, containing a file ``

1. Create the following hierarchy: `dir/` `dir/spécial` (i.e. the 3rd letter of the file name is a French e-acute)
2. Subscribe to `dir/` 3. Delete the file `spécial`

-> no events will be notified for the deletion because the file path
can't be found in the subscription tree

Using unicode aware search functions in BruteForceBackend::readTree
solves this.

[taratatach]

The one test that's failing because it takes more than 2s to complete runs in 52ms on my own machine which isn't a beast. Is it possible that the setup is longer on the CI?

[mischnic]

You could lengthen that timeout if you want to test that. But I don't think that is likely to be the problem

watcher/test/since.js

Line 53 in 2de6ab4

this.timeout(5000);

[benmccann]

@taratatach it looks like there's a merge conflict on this PR