rust: mostly avoid streaming zstd decompression
Streaming ZStd decompression seems slightly slower, and
the API we use makes it very inconvenient to re-use the
decompression context.
Instead of using that, use the buffer-backed version,
because we can give a reasonable-ish size estimate.
edition = "2018"
max_width = 79
wrap_comments = true
error_on_line_overflow = true