Finalize manipulation of wallet metadata

[Anviking]

Context

Before we create a proper SQL DB Store, we'd like to finalize the wallet metadata.

In the our current MVar DB layer we're not storing WalletMetadata. We'd like to do that.

The current WalletId is an UUID.

We want the wallet id to be deterministic. We do not want to use (and expose) the root public key directly for security reasons…

Decision

…instead, compute the wallet id using a base16/hex-encoded hash (e.g. Blake2b 128) of root xpub. And — store WalletMetadata in the DB.

Acceptance Criteria

1. WalletMetadata must be stored in the DBLayer
2. WalletId should be redefined as a hex-encoded Blake2b 128-hash of the root public key.

---

Development Plan

• Replace construction of the wallet id from UUID to an actual hash of the wallet root public key
• Add a property test to verify that any two wallets with the same mnemonics ends up with the same wallet id
• Make sure metadata are stored alongside the wallet state and can be retrieved

PR

Number	Base
#156	master
#158	master

QA

• Wallet metadata are now correctly created in the wallet layer when creating a wallet
• UUID has been replaced with an hex-encoded hash of the root public key for the wallet id (this is reflected in the golden tests) and visible through the type of WalletId as well (cf haddock
• I've extended properties for the wallet layer as well to check that the wallet id generation is both deterministic and injective (cf: Cardano.WalletSpec)
• Wallet Metadata are also now stored in the DB Layer (DB layer has been extended to cover for those cases, see here putWalletMeta and readWalletMeta)
• Also added extra tests for the wallet metadata and actually, tx history too in Cardano.Wallet.DB.MVarSpec

[piotr-iohk]

lgtm 👍