Allow `crossorigin` attribute in headScript

See https://developer.mozilla.org/en-US/docs/Web/HTML/Element/script#attr-crossorigin
#6634 - cs fixes - one attribute per line
#6634 - adding test to verify that the "crossorigin" attribute is supported

Ref: http://www.w3.org/TR/html5/scripting-1.html#attr-script-crossorigin
#6634 - adding `@group` annotation for newly introduced tests
Merge branch 'hotfix/#6634-allow-crossorigin-headscript-attribute'

Close #6634