(deep) disjunctive patterns in backend that don't support them (e.g. F*)

[W95Psp]

@franziskuskiefer wrote in #462

Disjunctive patterns aren't supported in the F* backend. They are supported since #306.

There is a test in https://github.com/hacspec/hax/blob/main/tests/pattern-or/src/lib.rs

This issue covers the case "deep" disjunctive patterns, eg:

fn f(x: &[u8]) -> u8 {
    match x {
        [] => 0,
        [(1|2|3),..] => 1,
        _ => 2
    }
}

Roadmap

F* doesn't support such patterns, we need a phase that will turn such such a match into multiple nested ones.