Add SQL query comment to aid debugging

[seanlinsley]

It'd be great if the SQL that pco_store generates had a SQL comment like this prefixed to the query:

/* file:a/b.rs */
SELECT * FROM ...

That would make it easier to track down the source of the query from pg_stat_statements, pganalyze, etc.

I haven't tested it but theoretically we can add this with #[track_caller]:

// Mark the function that needs to know its caller's location
#[track_caller]
fn log_call() {
    // Get the location of the caller
    let location = std::panic::Location::caller();
    
    // Extract the file path (returns &str)
    let file_path = location.file(); 
    
    // You can also get the line and column numbers
    let line_number = location.line();
    let column_number = location.column();

    println!("Called from file: {}, line: {}, column: {}", file_path, line_number, column_number);
}

// Example usage from different locations
fn main() {
    log_call();
    another_function();
}

fn another_function() {
    log_call();
}