Add support for normalizing UNC paths in the FileSystem, controlled by the FileSystemImpl.normalizeUNCPaths flag
Rename the duplicated-slash regular expression and add JSDoc
Assume the FileSystem is initialized within `_normalizePath`; initialize the singleton instance at module load
Merge pull request #6041 from adobe/iwehrman/normalize-UNC-paths

Correctly normalize UNC paths
Merge branch 'brackets' into iwehrman/consistent-file-caching