[Feature] Improvement: don't pull in all features when adding snarkVM dependency

[HarukaMa]

🚀 Feature

I think this is good to have: currently all snarkVM dependency declaration in snarkOS are using default features, which includes default feature rocksdb. Unfortunately, rocksdb itself is rather slow to build, and unless the library user is trying to run a full-fledged ledger, it would be an unnecessary component.

For example, I was trying to only link to snarkos-node-router-messages to have the message types for a P2P node implementation, but doing that would pull in rocksdb which I won't ever need.

This should be a really low priority one and probably can be done after mainnet launch.

Motivation

Better dev experience for users who use part of snarkOS as library.

Implementation

Cargo.toml changes to disable default features if a sub-component doesn't really rely on them.

Are you willing to open a pull request? (See CONTRIBUTING)