[php-di v7] Optimize compiled string definitions

[partikus]

Version compatible with PHP ^8.0 as a successor of #5

Details (copied from #5)

• run preg_replace_callback already during compilation

from:

    protected function get5ce3da5dc66c0791095127()
    {
        return \DI\Definition\StringDefinition::resolveExpression('path.cache', '{BASE_PATH}/application/cache', $this->delegateContainer);
    }

    protected function get5ce3da5dc66c3314070297()
    {
        return \DI\Definition\StringDefinition::resolveExpression('path.cache.app', '{path.cache}/file', $this->delegateContainer);
    }

to:

    protected function get5ce3da5dc66c0791095127()
    {
        return ''.$this->resolveStringPlaceholder('BASE_PATH', 'path.cache').'/application/cache';
    }

    protected function get5ce3da5dc66c3314070297()
    {
        return ''.$this->resolveStringPlaceholder('path.cache', 'path.cache.app').'/file';
    }

where resolveStringPlaceholder proxies to $this->delegateContainer->get()