Generic arrow properties and generic methods now have an erased runtime
value, their instance with every type parameter bound to unknown. Calls
through a round trip via any, a function result, an array element or a
class-backed interface call that value and convert the result to the
call's type, as JavaScript does. Direct calls on a known definition keep
their monomorphized path.
Fixes#905
Co-authored-by: Konstantin Mikheev <8560582+konmik@users.noreply.github.com>