Fix all memory leaks

[mvorisek]

fixes #1669

All tests must be able to run 1 000 000 times without any memory increase 😄

The following usecases are leaky by design:

minimal leak per iteration, leaks when the array is resized (4x, 8x, 16x, ...)

https://3v4l.org/JAMjY

if (!class_exists(Leaky::class)) {
    class Leaky
    {
        public static $arr = [];
    }
}
Leaky::$arr[] = count(Leaky::$arr);

leaks when php resizes class table (also in multiple of 2, but as many classes are normally already present, takes much more iterations to detect)

https://3v4l.org/jrqso (demo should include the code below in a look and the results depends if opcache is enabled)

new class() {};

[mvorisek]

I verified 1600 iterations of unit tests:

PHPUnit 9.5.10 by Sebastian Bergmann and contributors.

Runtime:       PHP 8.1.0RC3
Configuration: /__w/ui/ui/phpunit.xml.dist

...............................................................  63 / 497 ( 12%)
............................................................... 126 / 497 ( 25%)
.........................F..................................... 189 / 497 ( 38%)
............................................................... 252 / 497 ( 50%)
............................................................... 315 / 497 ( 63%)
............................................................... 378 / 497 ( 76%)
............................................................... 441 / 497 ( 88%)
........................................................        497 / 497 (100%)

You should really speed up these slow tests (>500ms)...
 1. 180392ms to run Atk4\Ui\Tests\JsTest:testNumbers
 2. 46438ms to run Atk4\Ui\Tests\DemosTest:testDemosStatusAndHtmlResponse with data set #59
 3. 46042ms to run Atk4\Ui\Tests\DemosTest:testDemosStatusAndHtmlResponse with data set #49
 4. 41555ms to run Atk4\Ui\Tests\DemosHttpNoExitTest:testDemosStatusAndHtmlResponse with data set #49
 5. 40208ms to run Atk4\Ui\Tests\DemosHttpTest:testDemosStatusAndHtmlResponse with data set #49
 6. 40152ms to run Atk4\Ui\Tests\DemosHttpNoExitTest:testDemosStatusAndHtmlResponse with data set #59
 7. 39672ms to run Atk4\Ui\Tests\DemosHttpTest:testDemosStatusAndHtmlResponse with data set #59
 8. 34168ms to run Atk4\Ui\Tests\DemosHttpNoExitTest:testDemosStatusAndHtmlResponse with data set #28
 9. 32179ms to run Atk4\Ui\Tests\DemosHttpTest:testDemosStatusAndHtmlResponse with data set #80
 10. 31640ms to run Atk4\Ui\Tests\DemosHttpTest:testDemosStatusAndHtmlResponse with data set #105
...and there are 404 more above your threshold hidden from view

Time: 01:25:12.599, Memory: 46.00 MB

There was 1 failure:

1) Atk4\Ui\Tests\DemosTest::testDemosStatusAndHtmlResponse with data set #19 ('basic/button.php')
Memory leak detected! (128.031 + 0.625 + 0.313 KB, 17 iterations)

FAILURES!
Tests: 497, Assertions: 2117919, Failures: 1.

the one failure is leaky experiment correctly detected.