Add support for external coordinator to tell two instances to federate their TAK servers - #194

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: docker/login-action@v3, mikepenz/action-junit-report@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/