Endpoint /api/v1/users/refresh_token generates new access token on request

Part of epic #3942

What type of user does this affect?

• volunteers

How should it operate? ⚙️🛠️

There should now be a api/v1/users/refresh_token route to generate new access tokens (api_token).

Acceptance Criteria

• Adds refresh_token post route to api/v1/ (/api/v1/users/refresh_token)
• Regenerates the current api_token and replaces old api_token_digest with hashed version of new token
• Route accepts refresh_token and returns session_blueprint data with new api_token

Helpful Links

API Folder Structure
Blueprint

Start in the app/controllers/api/v1 folder and read the existing session-related routes and the session_blueprint at app/blueprints/api/v1/session_blueprint.rb. Trace how API tokens and their digests are currently handled, then verify that the refresh_token POST route accepts a refresh token, replaces the digest, and returns the blueprint data with a new api_token.