PF previews do not display default values in added properties

[VenelinMartinov]

When previewing a resource change which adds a property in a Plugin Framework resource we do not display defaults applied to that new property. The reason for that is that the engine does not have access to the planned values and we do not apply defaults in Check for PF. Likely blocked on #2281

Example:

    ~ testprovider:index/test:Test: (update)
        [id=test-id]
        [urn=urn:pulumi:test::project::testprovider:index/test:Test::p]
      - keys: []

versus TF:

  ~ resource "testprovider_test" "res" {
        id  = "test-id"
      ~ key = [
          + "value",
        ]
    }

Also

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

versus TF:

+/- resource "testprovider_test" "res" {
      ~ id = "test-id" -> (known after apply)

      ~ key { # forces replacement
          ~ nested = "value" -> "default"
        }
    }

See TestDetailedDiffSet/attribute_with_default/changed_empty_to_null and TestDetailedDiffObject/nested_block_default_replace/changed_non-empty_to_empty