Support refresh token in token exchange grant type

[shashimalcse]

Is your suggestion related to an experience ? Please describe.
Based on the token exchange grant specification (https://datatracker.ietf.org/doc/html/rfc8693), a successful response may include the refresh token. With support for the token exchange grant type in the identity server (#16345), we should take this into consideration.

Describe the improvement
The improvement entails enabling the refresh token in the token exchange grant.

[shashimalcse]

We are closing this issue since we have completed all the backend support for token exchange. The UI support for enabling refresh grant for token exchange will be provided through #16390