Caching access token during BrowserIdcAuthPlugin authentication for subsequent/parallel session requests

Currently, running SQL queries via `BrowserIdcAuthPlugin` is done on a per-session basis. This can be tiresome when running queries across different sessions in parallel (e..g, dbt), where multiple browser pop-ups are triggered throughout the run duration. I would like to add a feature to cache the access token received during the token exchange process, so that future sessions will reuse the cached token instead of re-initializing a new session.

As the proposal involves storing the access token locally (whether it be via file/memory, plain-text/encrypted, etc.), would this be a security issue? Not sure if it would be a hard blocker before I open a PR for this feature proposal.

Start by tracing BrowserIdcAuthPlugin authentication through the token exchange and session initialization paths. Define the cache scope and storage security requirements, then verify that subsequent and parallel sessions reuse a valid token without triggering repeated browser pop-ups.

Written by the indexing model from the issue text.