feat: add asset picker opened and selected metrics

[ghgoodreau]

Explanation

References

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've communicated my changes to consumers by updating changelogs for packages I've changed
• I've introduced breaking changes in this PR and have prepared draft pull requests for clients and consumer packages to resolve them

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Note

Adds tracking for asset picker interactions in cross-chain swaps.

• Introduces Asset Picker Opened and Asset Selected events in utils/metrics/constants.ts
• Extends RequiredEventContextFromClient with payloads for these events (location, token/chain identifiers) and updates EventPropertiesFromControllerState to null for controller-derived props
• Wires bridge-controller to emit these events with base properties via #getEventProperties

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