fix(config): correctly parse env variables

[folex]

Before, they were split by _, which caused the following parsing behaviour:

[crates/server-config/src/resolved_config.rs:212] config_builder.extract()? = {
    "print_config": Bool(false),
    "aqua_pool_size": String("6"),
    "env": Object {
        "aqua": Object {
            "ipfs": Object {
                "external": Object {
                    "api": Object {
                        "multiaddr": String("/ip4/127.0.0.1/tcp/5001"),
                    },
                },
                "local": Object {
                    "api": Object {
                        "multiaddr": String("/ip4/127.0.0.1/tcp/5001"),
                    },
                },
            },
        },
    },
    "allowed": Object {
        "binaries": Array [
            String("azaza"),
        ],
    },
    "local": Bool(true),
    "no_banner": Bool(false),
    "allow_local_addresses": Bool(false),
}