NMS-19094: Replace xml with JSON when creating and updating an event

[Shahbaz-dataq]

External References

• Jira (Issue Tracker): https://opennms.atlassian.net/browse/NMS-19094

[Copilot]

Pull request overview

This PR replaces XML with JSON format when creating and updating events in the event configuration system. The changes primarily focus on updating the data flow to use JSON structures while maintaining backward compatibility with XML content for display purposes.

Key Changes:

• Added JSON structure mapping for event configuration events
• Updated store methods to use refreshEventConfigEvents instead of direct fetchEventsBySourceId calls
• Modified tests to verify the new fetch flow with proper source loading sequence

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 4 comments.

File	Description
ui/src/mappers/eventConfig.mapper.ts	Adds mapEventConfEventFromServer function to transform server events into JSON structure and includes JSON content in mapped events
ui/src/stores/eventConfigDetailStore.ts	Changes fetchSourceById to call refreshEventConfigEvents instead of fetchEventsBySourceId
ui/src/containers/EventConfigurationDetail.vue	Simplifies mount logic by removing redundant calls and adds debug logging
ui/tests/containers/EventConfigurationDetail.test.ts	Updates tests to verify the new source fetching flow and event loading sequence

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

[synqotik]

LGTM