feat(terraform): iterator argument support for dynamic blocks

[nikpivkin]

See documentation for details.

The iterator argument (optional) sets the name of a temporary variable that represents the current element of the complex value. If omitted, the name of the variable defaults to the label of the dynamic block ("setting" in the example above).

Now, using this argument can lead to false positives.

An example of the use of the iterator argument:

resource "aws_s3_bucket" "this" {
  dynamic versioning {
    for_each = ["true"]
    iterator = ver

    content {
      enabled = ver.value
    }
  } 
}

Which is equivalent to the following:

resource "aws_s3_bucket" "this" {
  dynamic versioning {
    for_each = ["true"]

    content {
      enabled = versioning.value
    }
  } 
}