feat(tracemetrics): Implement read-only view for equations in alerts

[narsaynorath]

This adds a skeleton that I'll be adding interactivity to. An existing equation (created through the API) can be viewed using this to show what an equation would look like

It closely mimics what we have for the Explore equation builder flow. Queries can't be deleted if they're referenced in equations. Everything gets a label. I'm only going to allow one equation at the moment (can open it up later). There is currently no way to transition from the regular single metric view to equations, but I'll make a PR to change that soon.

The following screenshot is of this equation (adjust URL to your viewing env): https://sentry.dev.getsentry.net:7999/monitors/7037172/edit/?project=1&statsPeriod=1h

[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

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[cursor]

Unstable no-op handlers cause repeated effect re-runs

Medium Severity

The inline () => {} no-op functions for handleExpressionChange and handleReferenceLabelsChange create new references on every render. EquationBuilder has a useEffect with onReferenceLabelsChange in its dependency array, so this effect (which does non-trivial work including new Expression(...) construction and extractReferenceLabels() computation) fires on every single render along with its cleanup. Similarly, handleExpressionChange being unstable causes EquationBuilder's internal useCallback to recreate each render. Since noop from lodash is already imported and provides a stable reference, these inline functions can be replaced with noop to avoid this unnecessary work.

 

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