Add support for safe keyword in foreign functions and statics

[Wasabi375]

fixes #1756

This is an alternate solution to implement this and would also close #1960. As I explained in the issue this is probably the best way to do this, but I might be wrong again. I thought the same when I created #1960 but here I am again creating a second PR for the same issue 🤷‍♂️ I guess we could just discuss this in the issue, but writing this out helped me think through the problem.

Open questions:

1. Are there any tests I should add for this? If so can you point me to an existing test that I could use to orient myself? I'm not sure I fully understand the test framework here.
2. This is a breaking change. I'm not sure how this is handled in this repo.