Optimize GraphQL "dry run" query

[rafal-ch]

The source of this issue is #623.

Initially, the idea was to remove all complex queries from fuel-core and make it part of the indexer's responsibility. But the SDK is deeply integrated with these basic queries, that we need to support them on fuel-core. For that, we need to optimize the following query by aggregating some information in the off-chain worker or adding new indexes to the database:

• The dry_run already allows the dry running of many transactions; we just need to forbid several dry run sub-queries inside of one query.

Extracted from the #1965, which initially covered optimizations for 3 different areas: balances, coins to spend, dry run.