Ability to airdrop/sharedrop/pay dividends of one asset to all holders of another.

As a `user/asset issuer` I want `to have a transfer_asset_to_asset_holders API call` so that `I can perform airdrops/sharedrops or dividend payouts`.

**Additional Context (optional)**

Case 1: I own asset COOLASSET and decide to airdrop 50% of the total 1000000 COOLASSET supply to holders of BTS. I issue the relevant amount to myself and use transfer_asset_to_asset_holders(500000, 'COOLASSET','BTS')

Case 2: As a gateway operator, I collect market fees on all assets I provide gateway services for. Once a month, I want to share 50% of all market fee profits to holders of my GATEWAYCOIN. So for each gateway asset, I withdraw market fees, calculate 50% profit share (e.g. say 500 GATEWAY.UIA1) and use transfer_asset_to_asset_holders(500,'GATEWAY.UIA1','GATEWAYCOIN')

I believe PBSA has already implemented most of the code needed for this in peerplays.

**Referencecs**
- [BSIP 20 - Introducing profit-sharing/dividends to Bitshares (UIA only)](https://github.com/bitshares/bsips/blob/master/bsip-0020.md)
- [Peerplays Profit Share Implementation](https://github.com/BunkerChainLabsInc/peerplays-profitshare) __(link to code needed)__

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

No source files or tests are named. Start by reading BSIP 20 and the linked Peerplays Profit Share Implementation, then map the requested transfer_asset_to_asset_holders API to the core asset and balance logic. Done means the requirements and test cases cover both airdrops and gateway profit-sharing payouts.

Written by the indexing model from the issue text.