Add Scale to SingleAssetVault (#5652)

* Add and Scale to VaultCreate
* Add round-trip calculation to VaultDeposit VaultWithdraw and VaultClawback
* Implement Number::truncate() for VaultClawback
* Add rounding to DepositWithdraw
* Disallow zero shares withdraw or deposit with tecPRECISION_LOSS
* Return tecPATH_DRY on overflow when converting shares/assets
* Remove empty shares MPToken in clawback or withdraw (except for vault owner)
* Implicitly create shares MPToken for vault owner in VaultCreate
* Review feedback: defensive checks in shares/assets calculations

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Co-authored-by: Ed Hennis <ed@ripple.com>

src/test/jtx/impl/Account.cpp

@@ -86,6 +86,14 @@ Account::Account(AcctStringType stringType, std::string base58SeedStr)
 {
 }
 
+Account::Account(std::string name, AccountID const& id)
+    : Account(name, randomKeyPair(KeyType::secp256k1), privateCtorTag{})
+{
+    // override the randomly generated values
+    id_ = id;
+    human_ = toBase58(id_);
+}
+
 IOU
 Account::operator[](std::string const& s) const
 {