Leveraging Compression API even when not streaming

[larabr]

Following up to #1717 : it'd be possible to set up a compression stream just in the context of the compression/decompression operation (see https://wicg.github.io/compression/#example-deflate-compress).

We should evaluate the performance impact, to understand if the change is beneficial.
If implemented, fflate could be imported only dynamically, for platforms that do not support the API.