Split loan principal and interest amount in listaccounthistory output (type: PaybackLoan)

#### What would you like to be added:
For each loan repayment I need to know the split between principal amount and interest amount. Currently it is presented as a single number (principal + interest) in listaccounthistory output (type: PaybackLoan).

#### Why is this needed:
This is required for accounting and tax compliance and is blocking defichain friendly businesses from creating proper tax report for state authorities.