Template literals are not escaped on interpolated strings

[yagizmunger]

In case of string interpolation, such as

It is correctly highlighted as interpolation. However, when template literal is used, such as

It is still highlighted as interpolation, even though Terraform does not interpolate. These cases should be handled differently, such as

See: https://github.com/hashicorp/hcl/blob/main/hclsyntax/spec.md#template-literals