Add support for interpolation

[Applelo]

Can you add the support for interpolation ?
See https://pugjs.org/language/interpolation.html

[Shinigami92]

Please provide me some code, so I can create a test for that

I heavily using TDD -> https://github.com/prettier/plugin-pug/tree/master/test/issues

[Applelo]

Ok no problem :) So I tried some different test with interpolation work but not with this case:

 - const el = 'div';
 - const test = 'hello';
 #{el}.test
   | !{text}