Db/fix predicate validation bug

[davidbloss]

Resolves #496

Problem

Validation incorrectly fails on valid predicate blocks.

Given the example config:

resource "opslevel_check_service_property" "example" {
  for_each = var.my_values
  ...
  predicate = {
    type  = "satisfies_jq_expression"
    value = ".${each.key} | my_filter"
  }
}

PredicateObjectToModel() incorrectly converts the predicate.value field into a known empty string, when in fact predicate.value has an unknown state during the first validation pass since ${each.key} hasn't been resolved yet.

Solution

Ensure PredicateObjectToModel() preserves the unknown state on the first validation pass.

Checklist

• I have run this code, and it appears to resolve the stated issue.
• This PR does not reduce total test coverage
• This PR has no user interface changes or has already received approval from product management to change the interface.
• Make a changie entry that explains the customer facing outcome of this change