Add partial repayment tracking to the indexer

[Hrom131]

Describe the feature

Describe the feature

Description

In the current version of the lending-indexer crate, it is assumed that the debt will be repaid in a single payment. Logic for partial debt repayment needs to be added to OffersTracker. When the debt is partially repaid, the collateral is also partially unlocked, which must also be taken into account.

Acceptance Criteria:

• Defining partial debt repayment in OffersTracker
• A new table containing records of debt repayment and collateral release
• Saving information about the offer's current debt