`no-expression-statements`: allow `Promise<void>` when `ignoreVoid` is `true`

## Suggestion

Currently `no-expression-statements` generates an error when `ignoreVoid` is `true` and the function being called returns `Promise<void>`. This is unexpected and it would be more uniform behavior if both `void` and `Promise<void>` return types were treated the same when `ignoreVoid` is set. 
