store new non-UTF-8 files raw and decode to deplay the contents

Because https://www.mercurial-scm.org/wiki/EncodingStrategy#The_encoding_tracking_problem says that roundtripping through UTF-8 is lossy

Created by  rohan  on February 25, 2021
UM5DLRPBCQZQBEDJDLDPKODOKLACUHZD6YL6S4JRNKW6JLPNUVSAC
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