better query error reporting

[1st1]

This is what we print now

gel.errors.EdgeQLSyntaxError: Missing parentheses around statement used as an expression
   ┌─ query:14:33
   │
14 │                                   with
   │                                   ^^^^ error

we need to include more code above/below for this to make sense.

[fantix]

Ah! We should drop code the following and reuse the same _format_error():

https://github.com/geldata/gel-python/blob/a5c880ed95a69041fecbe1dede53b8b2c2f9ba2f/gel/_internal/_codegen/_generator.py#L178-L205