Adding of FreeBSD platform to support/regular testing

<!-- Please only use this template for submitting feature requests --> **Why is this needed**: In order to support broader variety of open-source operating systems, it would be really helpful to also have FreeBSD as supported/regularly tested platform. This would be benefical also for grafana-plugin-sdk. **What would you like to be added**: Contemporary production FreeBSD versions (as of now, 14.3-RELEASE, and also 15.0-CURRENT that is going to be released later this year). **Who is this feature for?** For everyone interested in other than Linux/MacOS OS.