Fix symfony polyfills in scoper

[pdelre]

This adds symfony/polyfill-* files and classes to php-scoper's allow lists. It addresses failure to load the polyfills detailed in #2973 & humbug/php-scoper#440.

I tested this locally with the following set of commands pulled from https://github.com/symplify/symplify/blob/master/.github/workflows/build_scoped_packages.yaml#L38.

Build Scoped Package

git clean -fdx && rm -rf vendor
composer update --no-progress --ansi
packages/monorepo-builder/bin/monorepo-builder localize-composer-paths packages/easy-coding-standard/composer.json --ansi
composer update --working-dir packages/easy-coding-standard --ansi --no-dev
vendor/bin/php-scoper add-prefix packages/easy-coding-standard --output-dir packages-scoped/easy-coding-standard --config packages/easy-coding-standard/scoper.inc.php --force --ansi
composer dump-autoload --working-dir packages-scoped/easy-coding-standard --ansi --optimize --classmap-authoritative
packages/package-scoper/bin/package-scoper scope-composer-json packages-scoped/easy-coding-standard/composer.json --ansi
chmod 777 ./packages-scoped/easy-coding-standard/bin/ecs

Verify no Fatals occur

cd packages-scoped/easy-coding-standard
./bin/ecs init
sed -i 's|// SetList::PSR_12|SetList::PSR_12|' ecs.php
./bin/ecs check ./bin/ecs.php)

[TomasVotruba]

CI needs to pass before review

[pdelre]

I realize I've taken a liberty here, but I was unable to find a way to address humbug/php-scoper's expected Isolated\Symfony\Component\Finder\Finder usage.

[TomasVotruba]

Thank you 👍

[TomasVotruba]

I'm just building ECS prefixed and this does not work as expected.

Good news, we're not alone :) php-scoper is full of reports with same issues humbug/php-scoper#440

Some fixes from dev-master of php-scoper might help, but it has not been tagged yet :/

Another attempt: a58433f