[Symfony/Finder] Add support for mercurial version controls in ignoreVCSIgnored

in Symfony/Finder component , ignoreVCSIgnored uses .gitignore        
It will be nice to have support for [mercurial](https://www.mercurial-scm.org/wiki/.hgignore 
) .hgignore file


https://github.com/symfony/symfony/pull/30448#issuecomment-477120150