ref: Add span filtering to span first (15)

[sentrivana]

In span first, we're introducing a new span filtering init option called ignore_spans which allows to ignore spans at start time based on name and attributes.

• Spans ignored this way emit a new ignored client report (set via NoOpStreamedSpan.unsampled_reason).
• If a segment matches one of the rules in ignore_spans, the whole span tree will be ignored. The implementation achieves this by allowing NoOpStreamedSpans to be set on the scope in this one single case, so that their children can easily determine their segment was dropped.
• If a segment is not ignored but one of its children spans (regardless of depth) is, ONLY that one span will be ignored, not its whole subtree.

Spec: https://develop.sentry.dev/sdk/telemetry/spans/filtering/#filter-with-ignorespans

[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

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[github-actions]

Semver Impact of This PR

🟢 Patch (bug fixes)

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Codecov Results 📊

✅ 2159 passed | ⏭️ 115 skipped | Total: 2274 | Pass Rate: 94.94% | Execution Time: 5m 51s

All tests are passing successfully.

✅ Patch coverage is 100.00%. Project has 11694 uncovered lines.

Files with missing lines (4)

File	Patch %	Lines
tracing_utils.py	83.98%	⚠️ 111 Missing and 40 partials
scope.py	92.58%	⚠️ 63 Missing and 41 partials
_types.py	76.67%	⚠️ 7 Missing and 1 partials
consts.py	99.16%	⚠️ 2 Missing

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[alexander-alderman-webb]

looks good, see one non-blocking suggestion

[cursor]

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