linter: initial support of complex instanceof for if/else and ternary

[i582]

Description

1. Added processing in the if / else chain (including for expressions):

/**
 * @param mixed $a
 */
function f($a) {
  if ($a instanceof Foo) {
    exprtype($a, "\Foo");
  } else if ($a instanceof Boo) {
    exprtype($a, "\Boo");
  } else {
    exprtype($a, "mixed");
  }

  exprtype($a, "mixed");
}

2. Added processing for negation (including for expressions):

/**
 * @param Foo|Boo|Zoo $a
 */
function f($a) {
  if (!$a instanceof Foo) {
    exprtype($a, "\Boo|\Zoo");
  } else if (!$a instanceof Foo) {
    exprtype($a, "mixed");
  } else {
    exprtype($a, "\Foo");
  }
}

3. Added support for the ternary operator:

/**
 * @param Foo|Boo $a
 */
function f($a) {
  $_ = $a instanceof Foo ? 
  			exprtype($a, "\Foo") : 
  			0;

  $_ = $a instanceof Foo ? 
			exprtype($a, "\Foo") : 
			exprtype($a, "\Boo");

  $_ = isset($a->aaa) && $a->aaa instanceof Foo ? 
			exprtype($a->aaa, "\Foo") : 
			exprtype($a->aaa, "mixed");
}

/**
 * @param mixed $a
 */
function f($a) {
  $_ = $a instanceof Foo ? 
  			exprtype($a, "\Foo") : 
  			exprtype($a, "mixed");
  $_ = $a instanceof Foo ? 
  			exprtype($a, "\Foo") : 
  			($a instanceof Boo ? 
  				exprtype($a, "\Boo") : 
  				exprtype($a, "mixed"));
}

/**
 * @param Foo|Boo $a
 */
function f($a) {
  $_ = !$a instanceof Foo ? 
  			0 : 
  			exprtype($a, "\Foo");

  $_ = !$a instanceof Foo ? 
			exprtype($a, "\Boo") : 
			exprtype($a, "\Foo");

  $_ = isset($a->aaa) && !$a->aaa instanceof Foo ? 
			exprtype($a->aaa, "mixed") : 
			exprtype($a->aaa, "\Foo");
}

4. Added initial processing of variables in conditions:

if (($a = new Foo) && $a instanceof Foo) {
  exprtype($a, "\Foo");
}

if ((($a = new Foo) || ($a = 10)) && $a instanceof Foo) {
  exprtype($a, "\Foo");
} else {
  exprtype($a, "precise int");
}

Epic #1037
Fixes #370
#363

[quasilyte]

Please move closure improvements to another PR.
We can merge them right away then.

[i582]

Please move closure improvements to another PR.
We can merge them right away then.

Done.

[quasilyte]

We discussed some ! nesting.
If you think that it's not an issue right now, feel free to merge.