This commit changes the PHP code sniffer to use PSR-12 rules, as that ruleset will pick up a lot of the code style issues being flagged in PRs recently.

In order to set the baseline, all current core files have been reformatted to fit the ruleset.

- Convert all aliases to qualified class names (mainly facades)
- Reorder imports alphabetically
- Ensure last item in array has a trailing comma
- Strip out unused imports

This will allow us to use the ruleset in plugins as well

With new ruleset, it now passes

This command will allow developers to check code style against the Winter CMS code style rules in both the core and installed plugins.