Improvement to `capfire`

[samuelcolvin]

I found this useful, perhaps we should add it to capfire?

class TraceSummary(TypedDict):
    id: int
    message: str
    children: NotRequired[list[TraceSummary]]


@dataclass(init=False)
class LogfireSummary:
    traces: list[TraceSummary]
    attributes: dict[int, dict[str, Any]]

    def __init__(self, capfire: CaptureLogfire):
        spans = capfire.exporter.exported_spans_as_dict()
        spans.sort(key=lambda s: s['start_time'])
        self.traces = []
        span_lookup: dict[tuple[str, str], TraceSummary] = {}
        self.attributes = {}
        id_counter = 0
        for span in spans:
            tid = span['context']['trace_id'], span['context']['span_id']
            span_lookup[tid] = span_summary = TraceSummary(id=id_counter, message=span['attributes']['logfire.msg'])
            self.attributes[id_counter] = span['attributes']
            id_counter += 1
            if parent := span['parent']:
                parent_span = span_lookup[(parent['trace_id'], parent['span_id'])]
                parent_span.setdefault('children', []).append(span_summary)
            else:
                self.traces.append(span_summary)


@pytest.fixture
def get_logfire_summary(capfire: CaptureLogfire) -> Callable[[], LogfireSummary]:
    def get_summary() -> LogfireSummary:
        return LogfireSummary(capfire)

    return get_summary