F# Smoke Test

[cartermp]

This is tracking the adding an F# smoke test (or two, or three), and will help in #2057. It should use a some different and likely more "difficult" F# features:

• SRTP and inlining
• F# Enums
• Recursive DUs
• Higher-order functions

Although the goal isn't to have a file which uses every single feature of the F# language in different valid ways, it should serve as a pretty good roadmap of what needs to be addressed.

[cartermp]

@jkotas can we get an "F# Support" label so that if/when more issues are created it's easier to group them?