Relax rule: Allow tagged template string expressions (no-unused-expressions)
Relax rule: Allow tagged template string expressions (no-unused-expressions)

Fixes: https://github.com/feross/standard/issues/822

Fixes "Expected an assignment or function call and instead saw an
expression." error when using a standalone tagged template string like:

```js
var css = require('sheetify')

css`
  .js-yellow { color: #f7df1e }
  .bg-js-yellow { background-color: #f7df1e }
`
```

valedaemon/eslint-config-postmodern,feross/eslint-config-standard