Tracking PR for v0.5 release

[bobbinth]

This PR tracks progress for v0.5 release. The aim of this release is primarily to wrap up implementations various Merkle structures.

General

• Replace MerklePathSet with PartialMerkleTree #130
• Create a wrapper for Word #59
• hash bench #77

Sparse Merkle tree

As a part of this release we should close the following issues (one way or the other):

• Tracking issue: Sparse Merkle tree implementations #7
• Design compact Sparse Merkle tree #22
• Define general tree storage trait #30
• Implement compact sparse Merkle tree in Miden assembly #37
• Integrate sparse Merkle tree in advice provider #38
• Tiered sparse merkle tree requirements #91
• Implement MerkleStore::{with_tiered_smt, add_tiered_smt} #135

One question is what are we looking for in the Rust implementation of the tiered SMT. In my mind, we'd use it for account storage and vaults and so the requirements should be driven by the needs of the account object.

There are two other use cases for a tiered SMT: (1) account database, and (2) nullifier database. Both of these will probably require different implementations as they are going to be too large for pure in-memory implementation. So, we'll do them in future releases.

Merkle mountain range

Current implementation of the MMR is good enough for the needs of the chain database, but for user wallets, we do need to maintain partial MMR for own notes.

• Tracking issue: Implement Merkle mountain range #51
• Merkle mountain range partial #86