feat(multi-provider): Add Track Method Support to Multi-Provider

[jonathannorris]

This PR

This PR adds support for the track method to the Multi-Provider and Multi-Provider-Web, allowing tracking events to be sent across multiple underlying providers with customizable behaviour through evaluation strategies.

Features Added

🎯 Core Functionality

• Track Method: MultiProvider now implements the track method from the OpenFeature specification
• Strategy Integration: New shouldTrackWithThisProvider method allows strategies to control which providers receive tracking calls
• Error Resilience: Individual provider tracking failures don't break the flow - errors are logged and other providers continue

🛡️ Robust Error Handling

• Gracefully handles providers without track method implementation
• Logs errors but never throws - tracking failures won't break application flow
• Respects provider status (automatically skips NOT_READY/FATAL providers)

⚙️ Customizable Behavior

• Default: Tracks with all ready providers
• Custom Strategies: Override shouldTrackWithThisProvider for selective tracking
• Use Cases: Primary/backup provider scenarios, event-type filtering, etc.

Multi-Provider Usage Example

import { OpenFeature } from '@openfeature/server-sdk'
import { MultiProvider } from '@openfeature/multi-provider'

const multiProvider = new MultiProvider([
  { provider: new ProviderA() },
  { provider: new ProviderB() }
])

await OpenFeature.setProviderAndWait(multiProvider)
const client = OpenFeature.getClient()

// Tracked events will be sent to all providers by default
client.track('purchase', { targetingKey: 'user123' }, { value: 99.99, currency: 'USD' })

// Custom strategy for selective tracking
class CustomStrategy extends BaseEvaluationStrategy {
  shouldTrackWithThisProvider(strategyContext, context, eventName, details) {
    // Only track purchases with primary provider
    return eventName === 'purchase' && strategyContext.providerName === 'primary'
  }
}

Multi-Provider-Web Usage Example

import { WebMultiProvider } from '@openfeature/multi-provider-web'
import { OpenFeature } from '@openfeature/web-sdk'

const multiProvider = new WebMultiProvider([
  { provider: new ProviderA() },
  { provider: new ProviderB() }
])

await OpenFeature.setProviderAndWait(multiProvider)
const client = OpenFeature.getClient()

// Tracked events will be sent to all providers by default
client.track('user-conversion', { 
  value: 99.99, 
  currency: 'USD',
  conversionType: 'purchase' 
})

client.track('page-view', {
  page: '/checkout',
  source: 'direct'
})

[weyert]

Awesome, looks good :))