Add metrics parameter to logfire.configure()

[alexmojaki]

Internal discussion: https://pydantic.slack.com/archives/C05AF4A4WRM/p1727260278734989

This allows users to pass metrics=False to disable sending metrics entirely, since OTEL instrumentations often produce metrics where users only want/need the spans.

Alternatively users can pass logfire.MetricsOptions(...). For now the only option is additional_readers which replaces the existing top-level additional_metric_readers parameter of configure. In the future I want to add other options, including a way to filter specific metrics instead of just disabling them all, and a way to create metrics from spans in the SDK.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 100.00%. Comparing base (2304f95) to head (8ebb9d5).
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Additional details and impacted files

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  Coverage   100.00%   100.00%           
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  Files          131       131           
  Lines         9718      9754   +36     
  Branches      1275      1285   +10     
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+ Hits          9718      9754   +36     

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[Kludex]

I know it's not the point here, but do you know why did we choose dataclasses instead of TypeDicts on the parameters for configure? It looks very weird to instantiate those dataclasses as a user.

[alexmojaki]

#263 (comment)

It seems that PyCharm is handling a plain dict being passed to a TypedDict param more cleverly than I remember in terms of stuff like autocomplete. Maybe things have improved and this should be reconsidered.