Feature request: credit deal auto-repayment

[abitmore]

User Story

As a borrower, I would like that my debt can be (optionally) repaid automatically when it comes due and I have a sufficient balance in my account, so that I don't accidentally lose my collateral. If I don't have a sufficient balance in my account at that time, (optionally) repay as much as possible.

I also want my debt to have an optional auto-renewal when it comes to due. (This has been moved to a new issue: #2734 .)

Impacts
Describe which portion(s) of BitShares Core may be impacted by your request. Please tick at least one box.

• API (the application programming interface)
• Build (the build process or something prior to compiled code)
• CLI (the command line wallet)
• Deployment (the deployment process after building such as Docker, Travis, etc.)
• DEX (the Decentralized EXchange, market engine, etc.)
• P2P (the peer-to-peer network for transaction/block propagation)
• Performance (system or user efficiency, etc.)
• Protocol (the blockchain logic, consensus, validation, etc.)
• Security (the security of system or user data, etc.)
• UX (the User Experience)
• Other (please add below)

CORE TEAM TASK LIST

• Evaluate / Prioritize Feature Request
• Refine User Stories / Requirements
• Define Test Cases
• Design / Develop Solution
• Perform QA/Testing
• Update Documentation

[abitmore]

Done via #2735.