The compressor->decompress interface marks its third argument as non-const, which possibly doesn't make sense. While it is plausible that some compressors modify data in-place, this limitation is a problem for callers, e.g. the disaggregated storage block manager, where we need to deal with const input arguments and somehow pass them into decompress.

If there are good reasons for this to be non-const, then we should accept that some consumers of this will probably need to memcpy data around. Making this change is in the scope of this ticket.