Fix `vega_bridge_erc20_instance.whitelist_asset_admin()`

[Ashley Vega]

After #20, there's an error on MultisigControl startup:

Error: Invalid number of parameters for "whitelist_asset_admin". Got 2 expected 3!
    at module.exports (/app/migrations/2_contract_launch.js:16:38)
    at processTicksAndRejections (internal/process/task_queues.js:97:5)
    at Migration._deploy (/app/node_modules/truffle/build/webpack:/packages/migrate/Migration.js:73:1)
    at Migration._load (/app/node_modules/truffle/build/webpack:/packages/migrate/Migration.js:55:1)
    at Migration.run (/app/node_modules/truffle/build/webpack:/packages/migrate/Migration.js:171:1)
    at Object.runMigrations (/app/node_modules/truffle/build/webpack:/packages/migrate/index.js:150:1)
    at Object.runFrom (/app/node_modules/truffle/build/webpack:/packages/migrate/index.js:110:1)
    at Object.run (/app/node_modules/truffle/build/webpack:/packages/migrate/index.js:87:1)
    at runMigrations (/app/node_modules/truffle/build/webpack:/packages/core/lib/commands/migrate.js:269:1)
    at /app/node_modules/truffle/build/webpack:/packages/core/lib/commands/migrate.js:231:1
Truffle v5.1.41 (core: 5.1.41)

[Danny (Sacrificial Pancakes)]

The 3rd param is the Vega ID of that asset, which requires a governance vote to add. @DomVega wrote a script for this while we were on the call.

whitelist_asset_admin(address asset_source, uint256 asset_id, bytes32 vega_id)

[Ashley Vega]

After our long chat yesterday (ref), I think the docker container for MultisigControl needs a rejig:

• split ganache into separate long-running container, running only ganache, seeded with the standard mnemonic
• make multisigcontrol a one-shot, short-lived container that creates contracts on a specified chain