Add lender vaults tracker to the indexer

[Hrom131]

Describe the feature

Describe the feature

Description

When a borrower repays a debt, a Lender Vault UTXO is created and used. This UTXO stores an asset that the lender can redeem. A new LenderVaultsTracker needs to be added to the lending-indexer crate to detect the spending of Lender Vault UTXOs.

Acceptance Criteria:

• The LenderVaultsTracker module has been developed
• A new table has been created to store information about lender vaults
• OffersTracker has been updated to add lender vaults upon the first debt repayment