services/horizon: enable extraction of account and asset information from contract events for accurate ingestion filtering

[urvisavla]

Recently, we added the capability to extract account ids within smart contracts by analyzing contract events and extracting account information in stellar/go#5574. However, this does not address cases where ingestion filtering is applied to accounts as it follows a slightly different code path. We need to fix this and add test coverage.

Ingestion filtering can also be enabled by assets. If an asset is involved in a smart contract and the filtering is based on that asset, we should similarly extract the asset information from the events