Create a CI workflow for building and testing AtomVM on FreeBSD

[fadushin]

There is a way to run FreeBSD inside of virtualbox on MacOS runners in github actions.

Here is one example:

https://github.com/marketplace/actions/freebsd-vm

The idea here would be to use this action to create a CI so that we can also build and test AtomVM on FreeBSD.

[fadushin]

Closed via #866