[Observability][Synthetics] Move Exploratory View route into a separate app

[CoenWarmer]

📝 Summary

In order to allow the Synthetics team to better steward the development of the Exploratory View route in the Observability app, lets move the Exploratory View route to its own, dedicated Kibana application.

This is part of a larger effort to reorganize the Observability. More information in the epic #152783.

✅ Acceptance Criteria

• Move Exploratory View route into a separate application
• URL for new application should be /app/exploratory-view
• Git history should be retained as much as possible
• Links in Uptime and Synthetics should be updated to the new /app/exploratory-view

Steps after this ticket is completed (new tickets will be created)

• Update links in remaining app: APM
• Remove Exploratory View from Observability app
• Make sure /app/observability/exploratory-view redirects properly to app/exploratory-view

[elasticmachine]

Pinging @elastic/actionable-observability (Team: Actionable Observability)