CAMEL-23276: Add onReload hook to ContextServicePlugin for dev-mode route reloading

[Croway]

Summary

• Adds an onReload() lifecycle hook to ContextServicePlugin, invoked before routes are reloaded in dev mode
• RouteWatcherReloadStrategy now notifies all registered plugins via ContextServiceLoaderPluginResolver.onReload() before reloading routes
• Allows plugins to refresh bean references, re-read configuration, or update state before new routes start

Test plan

• Unit test RouteWatcherReloadStrategyOnReloadTest verifies plugins are invoked on reload
• Default no-op implementation verified not to throw

[github-actions]

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[sonarqubecloud]

Quality Gate failed

Failed conditions
0.0% Coverage on New Code (required ≥ 80%)

See analysis details on SonarQube Cloud