Cross test fix required empty blocks

[VenelinMartinov]

We were generating wrong HCL and Pulumi code in the cross test framework for empty required lists of other collections. This should fix both.

TF errors:

│ Error: Insufficient d2f0 blocks
│
│   on test.tf line 1, in resource "crossprovider_testres" "example":
│    1: resource "crossprovider_testres" "example" {
│
│ At least 1 "d2f0" blocks are required.

Pulumi errors:

Error: crossprovider:index:TestRes is not assignable from {}
  Cannot assign '{}' to 'crossprovider:index:TestRes':
    d3f0: Missing required property 'd3f0'

Also adds a test case for nested maxItemsOne properties - the second level empty test case is impossible to match because of the reduced information in the pulumi representation, right?

[VenelinMartinov]

superseded by #2011

EDIT: wrong PR

[VenelinMartinov]

Superseded by #2022