Function resolve_http 

pub async fn resolve_http(
    url: &str,
    method: Option<&str>,
    headers: &HashMap<String, String>,
    format: DataFormat,
    extract_expr: Option<&ExtractExpr>,
    timeout: Option<Duration>,
) -> Result<ResolvedValue, SourceError>

Resolve an HTTP source by fetching the URL and parsing the response.