Problem

The command okapi:upgrade-to-latest currently focuses on upgrading to the latest supported Okapi version, but it does not provide a read-only overview of which Okapi endpoints are available behind the
currently configured servers.
Administrators need a quick way to inspect available endpoints per server base URL before running upgrades or making configuration decisions.

Solution

Extend okapi:upgrade-to-latest with a new --list option.
When this option is used, the command should:

1. Read the current Okapi server configuration.
2. Build a distinct list of configured servers (by base URL).
3. Resolve and display available Okapi endpoints/versions for each server.
4. Exit without applying any upgrade changes.

Implementation should reuse ServerConfigUpgrade logic to keep endpoint/version discovery centralized and avoid duplicating configuration parsing logic in the CLI command.