Support node `interpolation` that wasn't wrapping in node `string_expression` for `#hmts-path?`

[n0099]

Given attrpath: (_) @_path (#hmts-path? @_path "services" "nginx" "virtualHosts" ".*" "locations" ".*" "extraConfig"), it would match attr path like services.nginx.virtualHosts."${host}".locations."/".extraConfig:
but not services.nginx.virtualHosts.${host}.locations."/".extraConfig:
The only difference between them is whether the interpolated attr path being wrapped in a string or just a plain interpolation.