Description:
This pull request implements the text-align-last css property.

Changes Made:
I created a protected function _text_align_last() in src/FrameReflow/Block.php file.
In the justify case (that is what i needed) i m doing a continue if not last line with
if ($line->br || $i !== $last_line_index) { **continue;** }
In reflow() function called this new function with $this->_text_align_last();

Testing:
Tested with PHPUnit with PHP Version 8.0.25 and works greatly.

Related Issues:
doing issue reported in github repository (#2311).