Add support for additional platforms to the core Vexil product

[bok-]

Swift supports a number of additional platforms such as Windows, Android and WebASM. We should expand support for the core Vexil product to as many of these as we can support.

To do this we would need:

• Any changes to the codebase needed to compile on the additional platforms
• Any tests required to validate those changes
• A way to run the tests on CI for those platforms