[PHP] New hint item for missing type at declaration places

### Description

Currently, PHP type system covers most of the cases. With ```mixed```, other unrepresented types can be represented by it. Another purpose of ```mixed``` is to discern whether people forgot to give a type or not. Adding types to all possible places is a good discipline. Netbeans need to provide additional item in editor hint to switch on and off to adjust this rule to the project policy.

### Use case/motivation

```php

The issue names no files, tests, or entry points. Start by locating NetBeans' PHP editor hint implementations and their tests, then verify coverage for untyped properties, parameters, return types, and promoted constructor properties; done means the hint can be enabled or disabled for the project policy and flags the shown cases.

Written by the indexing model from the issue text.