Insert top level type variables before typing quote pattern

[nicolasstucki]

The following code

case '{ type u; ($x: t, $y: t, $z: u) }

is desugared to

case '{ type t; type u; ($x: `t`, $y: `t`, $z: `u`) }

tried to fix #14708

[nicolasstucki]

It is impossible to infer the bounds of type t with this approach. We do infer bounds (badly) for type variables defined in the expression.

• We need another fix
• Or, we need to do disallow type inference of bounds (and use this desugaring)