tflint: Skip evaluation of module arguments if the module call is not evaluated

[wata727]

Fixes #1395

In Terraform, if count = 0 or for_each = [], the module is not evaluated and the module arguments are also not evaluated. So, the following configuration is valid:

variable "foo" {
  type = object({ attr = string })
  default = null
}

module "bar" {
  source = "./baz"
  count = 0

  argument = var.foo.attr
}

However, TFLint ignores the module's meta-arguments, so in this case var.foo.attr was evaluated and an error occurred.

Failed to prepare rule checking; failed to eval an expression in module.tf:10; Attempt to get attribute from null value: This value is null, so it does not have any attributes.

This PR makes the evaluation of modules aware of the meta-arguments. In the above example, var.foo.attr is not evaluated.