Revisit scss linting ordering rule

[vanitabarrett]

This is a stretch goal following on from #1740

Our linting checks that CSS properties are in a particular order. We kept this behaviour when switching from sass-lint to stylelint, but as a linting rule unique to GOVUK Frontend (stylelint-config-gds does not include this rule by default). This means our repo now has a custom linting rule compared to other projects which may use the config as is.

• Are we ok with having a custom rule?
• Do we think the ordering rule is necessary? What are the pros and cons?
• What would the impact be of turning the rule off?