[Sema] Propagate nonisolated attribute from wrapped property to the synthesized projectedValue property

[theblixguy]

Resolves #59380
Resolves #59494

We were not propagating the nonisolated attribute from the wrapped property to the synthesised projectedValue variable, thus triggering a main actor-isolated property '$<name>' can not be referenced from a non-isolated context error in some contexts when accessing the projectedValue.

@propertyWrapper 
struct Wrapper {
  var wrappedValue: Int { .zero }
  var projectedValue: Int { .max }
}

@MainActor
class Container {
  @Wrapper nonisolated var value

  deinit {
    _ = value // ok
    _ = $value // error
  }
}

[xedin]

Thank you! Could you please open a 5.7 PR for this as well?

[theblixguy]

@swift-ci please smoke test