Compress Wasm bytecodes when publishing

[jvff]

Motivation

Sometimes publishing application fails because the bytecodes are too large, and hit gRPC message size limits when sending the block proposal.

Proposal

Compress the bytecodes using Zstandard when including them in the SystemOperation::PublishBytecode. Use a new CompressedBytecode type to represent the compressed bytecode, and make it simple to convert to and from an uncompressed Bytecode.

Test Plan

CI should catch any regressions, since end-to-end tests cover publishing bytecodes and using them in applications.

Release Plan

A new major version must be released, because this breaks backward compatibility with bytecode publishing.

Links

• reviewer checklist

[christos-h]

Very nice! One thing I would say is that not all OS's ship with zstd. Since the crate used is a binding to zstd, perhaps we should have a fallback if it's not installed (gzip and then no compression at all).

Nevermind! Looks like we're already linking against it.

[Twey]

These are our current dynamically-linked libraries:

	librocksdb.so.9
	libgcc_s.so.1
	libm.so.6
	libc.so.6
	ld-linux-x86-64.so.2
	libsnappy.so.1
	libz.so.1
	libbz2.so.1
	liblz4.so.1
	libzstd.so.1
	liburing.so.2
	libstdc++.so.6
	libpthread.so.0

I'm not sure which of these are included with the standard Rust install, which would be okay since we currently require source builds, and which we should list as dependencies in the manual.