deprecated_interpolation: Prevent autofix from producing ambiguous attribute keys

[wata727]

Fixes #185

The current autofix for the terraform_deprecated_interpolation rule does not recognize expression context and will always fix "${var.foo}" to var.foo. However, if an object key is a deprecated interpolation, it must be wrapped in parentheses to prevent ambiguous attribute key errors.

This PR takes inspiration from hashicorp/terraform#26949 and fixes it so that autofixed code are wrapped in parentheses when the object key is a deprecated interpolation.

Before

locals {
  tags = {
    var.foo = "bar" # => ambiguous attribute key
  }
}

After

locals {
  tags = {
    (var.foo) = "bar"
  }
}