[vm] Instantiate types of parameters in constructor tear-offs from generic classes

When copying types of parameters from a constructor to a signature of
its tear-off, types should be instantiated to substitute class type
parameters with function type parameters.

For example,

  class A<T> {
    A(T x);
  }

  A.new // Should be 'A<S> Function<S>(S x)'

Without instantiation the parameter type would still reference class
type parameter:

  A<S> Function<S>(T x)

As a result, Closure::GetInstantiatedSignature would replace
class type parameters with dynamic (as tear-off doesn't have
instantiated type arguments) which is not correct:

  A<S> Function<S>(dynamic x)

TEST=co19/LanguageFeatures/Constructor-tear-offs/summary_A01_t01
(after https://github.com/dart-lang/co19/issues/1141 is fixed)

Issue https://github.com/dart-lang/sdk/issues/46231

Change-Id: I0517c400271e2a59ab0496a8cc39be51022768b4
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/209851
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Tess Strickland <sstrickl@google.com>