Convert EOL to UNIX-style to render MD properly (#8925)

Convert EOL to UNIX-style to render MD properly (#8925)

* Convert EOL to UNIX-style to render MD properly

* Update modules/markup/markdown/markdown.go

Co-Authored-By: zeripath <art27@cantab.net>
* Fix lint optimization

* Check for empty content before conversion

* Update modules/util/util.go

Co-Authored-By: zeripath <art27@cantab.net>
* Improved checks and tests

* Add paragraph render test

* Improve speed even more, improve tests

* Small improvement by @gary-kim

* Fix test for DOS

* More improvements

* Restart CI