Support Linux

[bilaalrashid]

Currently, the project can only support core Apple platforms due to variations between the open and closed-source versions of the core frameworks. Once these issues are resolved, Linux (#10) and Windows (#41) can then be officially supported.

This will either involve us waiting for Apple to reach feature parity between the two versions or will require us to implement the missing methods ourselves (and then ideally merge upstream if possible).

Additional context

This will also allow us to migrate the CI to Linux, which will result in cost savings.

[bilaalrashid]

Trying this after the Swift 6 migration, this now appears to work on Ubuntu so it's likely these discrepancies have been fixed.