Store payments in the state in addition / instead of events

[dmytrotkk]

Is your feature request related to a problem? Please describe.

Currently, the only way to retrieve payment information about past credit purchases is to scan the blockchain for PaymentReceived event, which makes it extra complicated to get the required info.

Describe the solution you'd like

Ideally, we should store payment info in the contract state with the following getters:

• get the current max payment id (for all addresses)
• get payment ids for an address
• get payment by id

Describe alternatives you've considered
A clear and concise description of any alternative solutions or features you've considered.

Additional context
Add any other context or screenshots about the feature request here.

[eduv09]

Missing getter to get last paymentId made in the system