The stage was structured in a way so that it supports many different
inputs, like, `archive` and in the future maybe trees, git checkouts.
This does not fit very well into the new input model, where instead
seperate `copy.tree` and `copy.files` stages might make more sense.
Since the stage is not been used anywhere, and mainly got added
as a way to get the ignition dracut module via an archive of a git
repo, remove the stage for now. A replacement will be brought back
in the future.
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