Extension not activated with `swift.searchSubfoldersForPackages` enabled

[award999]

To Reproduce
Steps to reproduce the behavior:

1. Open project linked in Diagnostics for files with spaces in name are not parsed #1630 (comment) in vscode
2. Enable swift.searchSubfoldersForPackages and reload the window
3. Notice swift extension never activates
4. Open a swift file in subfolder and notice it activates right away

Expected behavior
Should activate if Package.swift is in root or a subfolder

[plemarquand]

Verified with a5d7037