modules/zstd: Add literals decoding #1430

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@rw1nkler

The following contributors were found for this pull request:

✅ 96b6efd Author: @rw1nkler <rw****er@antmicro.com>
✅ 6d31c72 Author: @mtdudek <md***k@antmicro.com>
✅ d3048bf Co-Author: <rd*****ii@antmicro.com>
✅ 210e322 Author: @lpawelcz <pcz*****ki@antmicro.com>
✅ 7143a28 Author: @m-torhan <mt****n@antmicro.com>
✅ 9ec4ee3 Author: @RRozak <rr***k@antmicro.com>

(Only the first commit for a unique contributor is listed.)