Expected behavior for method and scheme when passed an `other` with a well-known name

[wingo]

What is the expected behavior if we set-method(other("GET")) ? Should it error, or should it resolve to method::get, or stay as other?

Similar for set-scheme(other("https")), but there since schemes are case-insensitive, we should also ask about set-scheme(other("HTTPS")).

[wingo]

JFYI, in Wasmtime set-method of Method::Other("GET") results in Method::Get, which to me seems like desired behavior. Similarly for Scheme::Other("https"). However Wasmtime currently doesn't apply case-insensitivity to schemes (bytecodealliance/wasmtime#11778 (comment)).