Asset history API

**User Story**

It would be helpful if we have an easy API to query for activities related to a specified asset.

It seems https://github.com/bitshares/bitshares-core/issues/2299 is the same issue.

By the way, not all supply / balance changes are tracked with virtual operations. PR #2074 is related.

**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 linked BitShares Core issue #2299 and related PR #2074 to determine the intended asset-activity API and which supply or balance changes must be represented. No source files or tests are named; done would require agreed requirements, implementation, and tests covering the requested asset history and relevant virtual-operation gaps.

Written by the indexing model from the issue text.