feat: Implement refreshCredentialsIfRequired for intermediate token r… (

#1583)

* feat: Implement refreshCredentialsIfRequired for intermediate token refresh

Implement `refreshCredentialsIfRequired`, called by `generateToken()`, to handle token refresh. It uses `refreshMargin` and `minimumTokenLifetime` to decide on synchronous or asynchronous refresh

* Add unit tests for the builder and refreshCredentials()

* Improve concurrency handling during credential refresh.

Introduced a refresh task to manage concurrent refresh requests, preventing redundant attempts and potential race conditions. This aligns the refresh mechanism with the pattern used in OAuth2Credentials and ensures more robust credential management.

* Update existing unit tests for compatibility and readability.

* Add unit tests for refreshCredentialsIfRequired.

* Fix a merge issue.

* Temporary add sonatype-snapshots repository and cel version to fix the build error.

* Remove duplicated code.

* Fix lint issue.

* Fix: Propagate credential refresh exceptions in blocking refresh.

* Change cel version

* Change cel version

* Add jsr305 dependency

* Fix Javadoc error

* Minor code readability enhancements.

* Revert "Fix Javadoc error"

This reverts commit 2157fdb.

* Address comments (add javadoc and use assertThrows in tests)

* Run format script