get_collateral_bids_by_account for dashboard page on the UI

**User Story**
For a given account, display the open/ existing collateral bids across all assets on the Dashboard page of Wallet UI. This is an independent Collateral Page.
The get_collateral_bids_by_account should be subsequently appended to get_full_accounts API

Reference UI ticket : https://github.com/bitshares/bitshares-ui/issues/2504

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

**Additional Context (optional)**
Add any other context about your request here.

## CORE TEAM TASK LIST
- [ ] Evaluate / Prioritize Feature Request
- [ ] Refine User Stories / Requirements
- [ ] Define Test Cases
- [ ] Design / Develop Solution
- [ ] Perform QA/Testing
- [ ] Update Documentation

Start by reviewing the get_collateral_bids_by_account and get_full_accounts API entry points, then compare the requirements with the referenced BitShares UI ticket. Done means the API exposes open or existing collateral bids for a given account across all assets and subsequently includes them in get_full_accounts, with defined test cases covering the response.

Written by the indexing model from the issue text.