PF peviews do not show show default values in old config

[VenelinMartinov]

When previewing a change in a resource using the Plugin Framework we incorrectly miss default values in old inputs

    ~ testprovider:index/test:Test: (update)
        [id=test-id]
        [urn=urn:pulumi:test::project::testprovider:index/test:Test::p]
      + key: {
          + nested: "value"
        }
Resources:
    ~ 1 to update
    1 unchanged

versus

  # testprovider_test.res will be updated in-place
  ~ resource "testprovider_test" "res" {
        id  = "test-id"
      ~ key = {
          ~ nested = "default" -> "value"
        }
    }

see TestDetailedDiffObject/attribute_default_no_replace/added

[VenelinMartinov]

~cc @t0yv0 I think you suspected this before and have suggested it to me. I've added some tests to confirm this.~

It's still a problem, PF does not apply defaults in check so the engine does not have access to the defaults. What is fixed here is that previously we would not show defaults in old values either.