refactor: FileUpdater (#123)

refactor: FileUpdater (#123)

* add missing changes from "refactor: FileUpdater"

* remove unnecessary OR expression

* remove unnecessary parent dir creation

* DRY logging function default

* test: get rid of now-obsolete nullLogger arguments

* simplify building sourceMaps in mergeAndUpdateDir

* simplify OR over all update indicators

* use fast-glob for file globbing

Until now we used our own glob implementation based on minimatch.

The only difference to the old implementation is, that not every parent
directory of a matched file is included in the result. However, since do
not pass the dirMaps out of this module and any missing dirs will be
created by fs-extra, that should be an advantage, if anything.

* Simplify mergePathMaps

* DRY file copying code

* Handle removals early & flatten logic

* Always show verbose log

* DRY file copying code further

* Improve comments

* Handle special files early & simplify

* Flatten logic

* Normalize dirMap keys to pass tests on Windows