…vailable; Revert #1583 (#1586)

* Test `infection.phar` works from subfolder where `vendor` folder is not available

This catches a bug introduced in #1583, where `./infection.phar -V` fails with

```
Warning: require(phar:///app/infection-builds/infection.phar/vendor/composer/installed.php): Failed to open stream: phar error: "vendor/composer/installed.php" is not a file in phar "/app/infection-builds/infection.phar" in phar:///app/infection-builds/infection.phar/vendor/composer/InstalledVersions.php on line 189
```

while `build/infection.phar` works as expected

* Revert "Do not use ocramius/package-versions (and do not break building PHAR this time) (#1583)"

This reverts commit 15015ab.

* Get back `build/` prefix

* Run Infection on PHP 8.1

* update symfony deps, add ReturnTypeWillChange attribute

* add check on VariadicPlaceholder

* remove conflict with symfony/console 4.1.5

* try to fix Return type of Mock_SplFileInfo_8d3a072c::getPath() should either be compatible with SplFileInfo::getPath() on 8.1

* whitelist PHP 8.1 constants in scoper.inc.php

* Add MockSplFileInfo mocks to work with Unit tests

* Increase possible direct issues

* fix another bunch of tests

* export SYMFONY_DEPRECATIONS_HELPER env variable as part of CI pipeline

* cast to int explicitly to avoid "Implicit conversion from float to int loses precision"

* fix pipeline

* remove continue-on-error on PHP 8.1

* remove ignore-platform-req from pipeline

* clean up pipeline

* import ReturnTypeWillChange to use section

* Run integration tests after E2E ones

* Fix "Tracing" benchmark test

…rns empty result (#1600)

* Use Symfony's `Process::fromShellCommandLin()` to execute a command

* Stop Infection execution with `0` exit code when git diff filter returns empty result (no files to be mutated)

* Stop Infection execution with `0` exit code when git diff filter returns empty result (no files to be mutated)

Fixes #1599

This will improve the speed of CI builds and immediately stop Infection execution.

Example: if `README.md` is updated on the root of the folder, we don't want/need to run Infection against the whole project.

* Depending on OS, check command line differently

https://www.php.net/manual/en/function.escapeshellarg.php

> On Windows, escapeshellarg() instead replaces percent signs, exclamation marks (delayed variable substitution) and double quotes with spaces and adds double quotes around the string.

…#1602)

* feat: Concat does not generate mutant when both operands are the same

Closes #1601

* Update ConcatTest.php

* use prettyPrint instead of prettyPrintExpr

* add clone per review suggestion

* suppress psalm issue - ImpureMethodCall

- per @maks-rafalko

* Update Concat.php

* suppress issue in psalm.xml

* Set XDEBUG_MODE for processes with coverage

Fixes #1473

* Add dg/bypass-finals to the conflict packages list

* Fix composer warnigns and indentation

Co-authored-by: maks-rafalko <b0rn@list.ru>

* Allow Symfony 6

* Fix composer warnings

Co-authored-by: maks-rafalko <b0rn@list.ru>