Create npm package

### Is your feature request related to a problem?

The multisig fonctionnality will surely be used in other web platform or node script. It is currently not possible

### Describe the solution you'd like

Create an npm package as an sdk that return the Transaction object from the libjs
for example
```javascript
import ArchethicVault from "@archethicjs/vault"
import Archethic from "@archethichjs/sdk"

const archethic = new Archethic("endpoint")
const vault = ArchethicVault.new(archehtic, "multisigAddress")
const tx = vault.newTransaction().addUcoTransfer("address", amount).build("seed", index)

tx.send().then(() => console.log("ok")).catch(() => console.log("error"))

console.log(vault.getSetup())
// {voters: [], signatureThreashold: 2 ...}
console.log(vault.getPendingTransaction())
// [{id: 3, data: ...}]
```

### Additional context

_No response_

### Epic

_No response_

Start by reviewing the existing libjs implementation and the requested web/Node usage example to identify the package boundary and exposed operations. Done means an npm SDK is available that exposes the shown vault and transaction flow and returns the Transaction object for external platforms and scripts.

Written by the indexing model from the issue text.