New rule to disallow use `self::` for non-static method calls

[f1mishutka]

Please add new rule to disallow use self:: for non-static method calls ($this-> should be used instead).

Example:

class SomeClass
{
  public function NonStaticMethod(): void
  {
    //do something
  }
  
  public function AnotherMethod(): void
  {
	$this->NonStaticMethod(); //normal way to call non-static methods
	
	self::NonStaticMethod(); // This is where sniff should raise error
  }
}

Using self:: to call non-static methods is formally acceptable in PHP, but is a marker of some leftovers after refactoring or just a bad design.

Thank you for the great product!