enable graphql tracing & machine readable logging option

[Voxelot]

This PR enables API error logging via tracing middleware both at the axum and the async_graphql layer.

Now when a bad request is made, the error will appear in the fuel-core logs like this:

Mar 21 18:57:05.682  INFO fuel_core::service::graph_api: Binding GraphQL provider to 127.0.0.1:4000
Mar 21 18:57:54.568 ERROR request:execute:field{path=dryRun parent_type=Mutation return_type=[Receipt!]!}: async_graphql::graphql: error=unexpected block execution error TransactionIdCollision(0x656da2b4912aa59d2beee8a36fa352e98efdd89a063a556b910ef4b1531d7733)

It also adds the HUMAN_LOGGING env var, which allows for json structured logging in deployed environments. This will make it easier to search & filter logs using elastic search for example.

HUMAN_LOGGING=false cargo run -p fuel-core

{"timestamp":"Mar 21 21:22:15.564","level":"INFO","fields":{"message":"Binding GraphQL provider to 127.0.0.1:4000"},"target":"fuel_core::service::graph_api"}

[vlopes11]

LGTM.

We should consider also to always log to stderr

[Voxelot]

I think that's how it currently works in all cases due to

.with_writer(std::io::stderr)

[rfuelsh]

lgtm!