Added Lines Before Namespace Fixers

NoBlankLinesBeforeNamespaceFixer is a contrib level fixer, and OneBlankLinesBeforeNamespaceFixer is a symfony level fixer. This also includes some utils refactoring and improvements.
Tests and description dont say that, and you use it on a whitespace token. Indeed it was designed for docblocks, so method rename might be wise. and have tests that show this is about docblocks.