[IMPROVEMENT] Refactor the interface definitions

[ansjcy]

Is your feature request related to a problem?

Currently there's no good interfaces/types definitions for query insights dashboards. We need to refactor the code to improve the maintainability.

What solution would you like?

For example, requests and responses to top n queries APIs are all defined as any. We should define concrete types for them instead.

What alternatives have you considered?

N.A.

[ansjcy]

Triage - We need to pick this up by 2.18.