`--debug-fork` should merge data when querying the subgraph, as well as at indexing time

Do you want to request a feature or report a bug?
Bug

What is the current behavior?

A graph-node run with --debug-fork returns empty data for all queries

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem.

Providing a short video where I run through all this. See video at timestamp 1:08 for proof of empty query results.

Repro steps:

1. Run forked mainnet ganache node with:
   npx ganache -h="0.0.0.0" --fork.url="https://eth-mainnet.alchemyapi.io/v2/$ALCHEMY_API_KEY" --fork.deleteCache

2. Run local ipfs & postgres nodes

3. Run local graph node with --fork-base ethereum-rpc of local ganache node, like so:
   cargo run -p graph-node --release -- --postgres-url postgresql://graph-node:let-me-in@0.0.0.0:5432/graph-node --ethereum-rpc mainnet:http://0.0.0.0:8545 --ipfs 0.0.0.0:5001 --debug --fork-base https://api.thegraph.com/subgraphs/id/

4. Create and deploy subgraph to local graph-node
   graph create fiatdao/fiat-subgraph --node http://0.0.0.0:8020
graph deploy fiatdao/fiat-subgraph --ipfs http://0.0.0.0:5001 --node http://0.0.0.0:8020 --debug-fork QmeHfNKsT8AupfXzpMKnG6k61KNUgm4mghCH827xcprWPA

• Visit local subgraph query ui. In my case, http://0.0.0.0:8000/subgraphs/name/fiatdao/fiat-subgraph. Query any models, you will see an empty response, rather than the results you would expect from querying the hosted subgraph node at the same block number.

What is the expected behavior?

When querying graph-node configured to use a forked subgraph and local mainnet forking node, I would expect:

1. My queries to the local graph-node to return the same value as the hosted node for any given query at the same block

2. When committing transactions which emit events on my local ganache node, my local graph-node should index those events on my local node

NOTE: The end goal of all this is to create a testing environment extremely close to mainnet for end-to-end testing purposes. Does what I'm trying to do here make sense? Does anyone have suggestions on how to get a close to mainnet environment for e2e tests?

Reproduce the issue using the listed Ganache, local IPFS/PostgreSQL, graph-node, --fork-base, and --debug-fork commands, then compare a local GraphQL query with the hosted subgraph at the same block. Done means existing forked data is returned for matching queries and events from local Ganache transactions are indexed locally.